it引导主语从句和it做形式主语还有强调句型的区别 强调句和形式主语IT引导的主语从句的区别
it \u505a\u5f62\u5f0f\u4e3b\u8bed\u5f15\u5bfc\u7684\u4e3b\u8bed\u4ece\u53e5\u548c\u5f3a\u8c03\u53e5\u578b\u7684\u533a\u522b\u6211\u89c9\u5f97\u662f B
it was \u3002\u3002\u3002that\u662f\u5f3a\u8c03\u53e5\u578b
\u5f3a\u8c03\u53e5\u578b\u65f6\uff0c\u901a\u5e38\u6307\u7684\u662f\uff1a"It be\u2026that\u2026"\u8fd9\u4e00 \u7ed3\u6784\uff08\u7b80\u79f0It-type\u5f3a\u8c03\u53e5\uff09\u3002
\u4f8b\u5982\uff1a
It is not only blind men who make such stupid mistakes. \u51b3\u4e0d\u53ea\u662f\u76f2\u4eba\u624d\u72af\u8fd9\u6837\u611a\u8822\u7684\u9519\u8bef\u3002
It was the goat's eyes that he had seen in the darkness. \u4ed6\u5728\u9ed1\u6697\u4e2d\u770b\u5230\u7684\u5c31\u662f\u8fd9\u53ea\u5c71\u7f8a\u7684\u773c\u775b\u3002
It-type\u5f3a\u8c03\u53e5\u7684\u7279\u5f81\u662f\uff1a\u5982\u679c\u6211\u4eec\u628a"It be\u2026that\u2026"\u4ece\u53e5\u4e2d\u5212\u53bb\uff0c\u6240\u5269 \u7684\u6b63\u597d\u662f\u4e00\u4e2a\u5b8c\u6574\u7684\u53e5\u5b50\u3002\u4f8b\u5982 \u4e0a\u9762\u7b2c\u4e00\u53e5\u7ecf\u8fc7\u5904\u7406\u540e\u5c31\u6210\u4e86\uff1a
Not onlt blind men make such stupid mistakes.
\u5b83\u7684\u610f\u601d\u4ecd\u7136\u662f\u5b8c\u6574\u7684\uff0c\u53ea\u662f\u5f3a\u8c03\u610f\u5473\u5df2\u7ecf\u5931\u53bb\u3002\u5b9e\u9645\u4e0a"It be\u2026that\u2026" \u53ea\u4e0d\u8fc7\u662f\u4e00\u4e2a\u6846\u67b6\u800c\u5df2\uff0c\u5b83\u7684\u5404 \u90e8\u4efd\u5728\u53e5\u5b50\u4e2d\u5747\u4e0d\u62c5\u4efb\u6210\u4efd\u3002
It-type\u5f3a\u8c03\u53e5\u901a\u5e38\u53ef\u7528\u6765\u5f3a\u8c03\u53e5\u5b50\u7684\u4e3b\u8bed\u3001\u5bbe\u8bed\u3001\u72b6\u8bed\u3002
\u4e00 . \u6ce8\u610f\u5f3a\u8c03\u53e5\u578b\u7684\u7ed3\u6784
\u201c It is /was + \u88ab\u5f3a\u8c03\u90e8\u5206 + who/ that + \u5176\u5b83\u90e8\u5206\u201d\uff0c\u6b64\u7ed3\u6784\u5e38\u8bd1\u4e3a\u201c\u662f\u2026\u2026\uff1b\u2026\u2026\u6b63\u662f\u201d\u3002\u5176\u7279\u70b9\u662f\uff1a\u53bb\u6389\u5f3a\u8c03\u7ed3\u6784\u201c It is / was \u2026 who / that\u2026 \u201d\u6216\u7ecf\u8fc7\u8bed\u5e8f\u8c03\u6574\u540e\uff0c\u539f\u53e5\u4ecd\u6210\u7acb\u3002\u5982\uff1a
It was about 600 years ago that the first clock with a face and an hour hand was made.
\u5982\u679c\u628a It was\u2026 that \u53bb\u6389\u540e\uff0c\u53e5\u610f\u4ecd\u5b8c\u6574\uff0c\u4e0d\u7f3a\u4efb\u4f55\u6210\u5206\uff0c\u5373\u539f\u53e5\u4ecd\u6210\u7acb\u3002
\u4e8c . \u6ce8\u610f\u8c13\u8bed\u52a8\u8bcd\u7684\u4eba\u79f0\u548c\u6570\u4e0e\u6240\u5f3a\u8c03\u7684\u4e3b\u8bed\u7684\u4e00\u81f4\u6027
\u5728\u5f3a\u8c03\u53e5\u578b\u4e2d\uff0c\u5f53\u5f3a\u8c03\u4e3b\u8bed\u65f6\uff0c\u5176\u540e\u7684\u8c13\u8bed\u52a8\u8bcd\u5e94\u548c\u88ab\u5f3a\u8c03\u6210\u5206\u7684\u4eba\u79f0\u548c\u6570\u4fdd\u6301\u4e00\u81f4\u3002\u5982\uff1a
It is the ability to do the job that matters not where you come from or what you are.
\u5f3a\u8c03\u7684\u4e3b\u8bed the ability to do the job \u662f\u5355\u6570\uff0c\u56e0\u6b64\u8c13\u8bed\u52a8\u8bcd matter \u4e5f\u5e94\u7528\u76f8\u5e94\u7684\u5355\u6570\u5f62\u5f0f matters \u3002
\u4e09 . \u6ce8\u610f who \u548c that \u7684\u9009\u7528
\u5728\u5f3a\u8c03\u53e5\u578b\u4e2d\uff0c\u82e5\u88ab\u5f3a\u8c03\u90e8\u5206\u662f\u4e3b\u8bed\uff0c\u4e14\u6307\u4eba\u65f6\uff0c\u53ef\u7528 who \u4ee3\u66ff that \uff1b\u82e5\u88ab\u5f3a\u8c03\u90e8\u5206\u662f\u5bbe\u8bed\uff0c\u4e14\u6307\u4eba\u65f6\uff0c\u53ef\u7528 whom \u4ee3\u66ff that \uff1b\u4f46\u82e5\u88ab\u5f3a\u8c03\u90e8\u5206\u662f\u72b6\u8bed\u65f6\uff0c\u5219\u53ea\u80fd\u7528 that \uff0c\u5373\u4f7f\u6307\u65f6\u95f4\u3001\u5730\u70b9\u3001\u539f\u56e0\u7b49\uff0c\u4e5f\u4e0d\u80fd\u7528 when \uff0c where \u6216 because \u7b49\u66ff\u4ee3\u3002\u5982\uff1a
It was my sister whom I met in the street yesterday.
It was only when I reread his poems recently that I began to appreciate their beauty.
It was for this reason that her uncle moved out of New York and settled down in a small village.
\u56db . \u6ce8\u610f\u8be5\u53e5\u578b\u4e00\u822c\u4e0d\u5f3a\u8c03\u8c13\u8bed\u52a8\u8bcd
\u5f3a\u8c03\u53e5\u578b\u901a\u5e38\u5f3a\u8c03\u4e3b\u8bed\u3001\u5bbe\u8bed\u548c\u72b6\u8bed\uff0c\u4e00\u822c\u4e0d\u5f3a\u8c03\u8c13\u8bed\u3002\u9700\u5f3a\u8c03\u8c13\u8bed\u65f6\uff0c\u8981\u5728\u8c13\u8bed\u52a8\u8bcd\u539f\u5f62\u524d\u9762\u52a0\u4e0a\u52a9\u52a8\u8bcd do \uff0c does \u6216 did \uff0c\u5c24\u5176\u662f\u5728\u7948\u4f7f\u53e5\u6216\u80af\u5b9a\u53e5\u4e2d\uff0c\u7528\u6765\u52a0\u5f3a\u8bed\u6c14\u3002\u5982\uff1a
Do tell me where on earth you are now!
Boys and girls , let me tell you something that does sound strange.
To my surprise, he did come here on time last night.
\u4e94 . \u6ce8\u610f\u533a\u5206\u542b\u6709 Not until \u7684\u5012\u88c5\u7ed3\u6784\u548c\u5f3a\u8c03\u7ed3\u6784
Not until \u7528\u4e8e\u53e5\u9996\u65f6\uff0c\u4e3b\u8bed\u548c\u8c13\u8bed\u901a\u5e38\u7528\u5012\u88c5\u8bed\u5e8f\u3002\u5982\u679c\u662f\u590d\u5408\u53e5\uff0c\u90a3\u4e48\u4e3b\u53e5\u7528\u5012\u88c5\u8bed\u5e8f\u3002\u4f46\u5728\u201c It is / was not until \u2026. that \u201d\u53e5\u578b\u4e2d\uff0c that \u540e\u7684\u4e3b\u8c13\u4e0d\u5012\u88c5\u3002\u5982\uff1a
It was not until she took off her dark glasses that I realized she was a famous film star.
\u672c\u53e5\u662f\u7531 I didn't realize she was a famous film star until she took off her dark glasses \u53d8\u5316\u800c\u6765\u7684\u3002\u547d\u9898\u8005\u6709\u610f\u5c06\u72b6\u8bed\u4ece\u53e5 until she took off her dark glasses \u7f6e\u4e8e It was \u2026 that \u8fd9\u4e2a\u5f3a\u8c03\u53e5\u578b\u4e2d\uff0c\u8003\u67e5\u8003\u751f\u7684\u5224\u65ad\u80fd\u529b\u3002\u6b64\u53e5\u8fd8\u53ef\u7528\u5012\u88c5\u7ed3\u6784\u6765\u8868\u8fbe\u3002\u5982\uff1a
Not until she took off her dark glasses did I realize she was a famous film star.
\u516d . \u6ce8\u610f\u5f3a\u8c03\u53e5\u578b\u4e0e\u4e3b\u8bed\u4ece\u53e5\u201c It is /was\u2026 that\u2026 \u201d\u7684\u533a\u522b
\u4e3b\u8bed\u4ece\u53e5\u4e2d It is / was \u540e\u901a\u5e38\u6709\u540d\u8bcd\u6216\u5f62\u5bb9\u8bcd\u4f5c\u8868\u8bed\uff0c\u800c\u5f3a\u8c03\u53e5\u578b\u4e2d It is/ was \u540e\u662f\u5bf9\u4e3b\u8bed\u3001\u5bbe\u8bed\u6216\u72b6\u8bed\u7684\u5f3a\u8c03\u6210\u5206\u3002\u5176\u5224\u522b\u65b9\u6cd5\u662f\uff1a\u53bb\u6389\u5f3a\u8c03\u53e5\u5f0f\u7ed3\u6784\u6216\u7ecf\u8fc7\u8bed\u5e8f\u8c03\u6574\u540e\uff0c\u539f\u53e5\u4ecd\u6210\u7acb\u3002\u8fd9\u4e5f\u662f\u5f3a\u8c03\u53e5\u578b\u4e0e\u4e3b\u8bed\u4ece\u53e5\u53ca\u5176\u5b83\u53e5\u5f0f\u7684\u91cd\u8981\u533a\u522b\u4e4b\u4e00\u3002\u5982\uff1a
It is a fact that English is being accepted as an international language.
Was it during the Second World War that he died?
\u770b\u5230\u7b2c\u4e00\u4e2a\u4f8b\u53e5\u4e86\u5417\uff1f
\u597d\u50cf\u6ca1\u6709\u4e00\u697c\u7684\u90a3\u79cd\u8bf4\u6cd5\uff0c\u4e0d\u8fc7\u6211\u53ea\u662f\u4e2a\u521d\u4e2d\u751f\uff0c\u5177\u4f53\u63a5\u89e6\u8fd9\u4e2a\u8bed\u6cd5\u7684\u673a\u4f1a\u5f88\u5c11
\u8fd9\u4e24\u4e2a\u95ee\u9898\u63d0\u5f97\u975e\u5e38\u6709\u6c34\u5e73\uff0c\u8bf4\u53e5\u9898\u5916\u8bdd\uff0c\u697c\u4e3b\u6211\u80fd\u95ee\u95ee\u60a8\u7684\u5e74\u9f84\u5417\uff1f
\u4e0b\u9762\u6211\u6765\u89e3\u91ca\uff1a
\u95ee\u98981\uff1a
\u5f62\u5f0f\u4e3b\u8bed\u662f\u4e00\u4e2a\u4ee3\u8bcd\uff0c\u7528\u6765\u201c\u4ee3\u201d\u53e5\u5b50\u7684\u771f\u6b63\u4e3b\u8bed\uff0c\u4e5f\u5c31\u662f\u8bf4\u201c\u53ef\u4ee5\u5b9e\u73b0\u548c\u771f\u6b63\u4e3b\u8bed\u6362\u4f4d\u7684\u90a3\u4e2aIT\uff0c\u5c31\u662f\u5f62\u5f0f\u4e3b\u8bed\u201d\uff0c\u53ef\u662f\u697c\u4e3b\u6240\u4e3e\u7684\u53e5\u5b50\u80fd\u6362\u4f4d\u5417\uff1f
\u4ece\u8868\u9762\u4e0a\u770b\uff0c\u7b2c\u4e00\u53e5\u8bdd\u8bf4\u6210\u201cWho did the experiment in the lab yesterday evening was my father.\u201d\u597d\u50cf\u6ca1\u6709\u4ec0\u4e48\u8bed\u6cd5\u9519\u8bef\uff0c\u4f46\u662f\u8fd9\u91cc\u5374\u5b58\u5728\u81f4\u547d\u7684\u903b\u8f91\u9519\u8bef\u3002
\u5982\u679c\u53e5\u5b50\u4e3b\u8bed\u662fWho\u5f15\u5bfc\u7684\u4e3b\u8bed\u4ece\u53e5\uff0c\u90a3\u4e48\u52a8\u4f5c\u7684\u53d1\u51fa\u8005\u5c31\u6210\u4e86\u201c\u6211\u7238\u7238\uff08who\u662f\u8fde\u63a5\u4ee3\u8bcd\uff09\u6628\u665a\u5728\u5b9e\u9a8c\u5ba4\u91cc\u505a\u5b9e\u9a8c\u201d\u3002
\u6ce8\u610f\uff1a\u201c\u6211\u7238\u7238\u6628\u665a\u5728\u5b9e\u9a8c\u5ba4\u505a\u5b9e\u9a8c\u201d\u8fd9\u662f\u4e00\u4ef6\u4e8b\uff0c\u53ef\u4e0d\u662f\u4e00\u4e2a\u4eba\uff0c\u6240\u4ee5\u540e\u9762\u600e\u4e48\u80fd\u63a5\u201cwas my father \u201d\u5462\uff1f\u5982\u679c\u8fd9\u6837\u5199\uff0c\u90a3\u4e48\u53e5\u5b50\u76f4\u8bd1\u8fc7\u6765\u5c31\u662f\u201c\u6211\u7238\u7238\u6628\u665a\u5728\u5b9e\u9a8c\u5ba4\u91cc\u505a\u5b9e\u9a8c\u662f\u6211\u7238\u7238\u3002\u201d\u8fd9\u8bed\u8a00\u662f\u4e0d\u662f\u5f88\u540e\u73b0\u4ee3\uff1f
\u90a3\u4e48\u8fd9\u53e5\u8bdd\u80fd\u4e0d\u80fd\u6539\u5bf9\u5462\uff1f
\u7b54\u6848\u662f\u80fd\uff0c\u800c\u4e14\u53ef\u4ee5\u6539\u5f97\u975e\u5e38\u6f02\u4eae\uff0c\u975e\u5e38\u5730\u9053\uff0c\u53ea\u8981\u52a0\u4e00\u4e2a\u4ee3\u8bcd\u5c31\u53ef\u4ee5\u4e86\uff0c\u6211\u628a\u5b83\u6539\u6210\u201cHe who did the experiment in the lab yesterday evening was my father.\u201d
\uff08\u987a\u4fbf\u8bf4\u4e00\u53e5\uff0c\u867d\u7136\u5f88\u591a\u4eba\uff0c\u4e5f\u5305\u62ec\u7edd\u5927\u591a\u6570\u8001\u5e08\uff0c\u90fd\u559c\u6b22\u5199\u201cThe man who\u2026\u2026\u201d\uff0c\u4f46\u662f\u6709\u82f1\u6587\u9605\u8bfb\u4e60\u60ef\u7684\u4eba\u4e00\u822c\u90fd\u8ba4\u4e3a\u201cHe/She who\u2026\u2026\u201d\u7684\u8868\u8fbe\u66f4\u52a0\u5730\u9053\uff0c\u5f53\u7136\u524d\u8005\u4e5f\u6ca1\u6709\u4efb\u4f55\u9519\u8bef\u3002\uff09
\u53d1\u73b0\u4e86\u4e48\uff1f\u8fd9\u4e48\u4e00\u6539\uff0c\u201cWho\u201d\u5f15\u5bfc\u7684\u4ece\u53e5\u5c31\u6210\u4e86\u5b9a\u8bed\u4ece\u53e5\uff0c\u800c\u53e5\u5b50\u7684\u4e3b\u5e72\u5219\u6210\u4e86\u201cHe was my father.\u201d\uff0c\u903b\u8f91\u9519\u8bef\u6d88\u5931\u4e86\u3002
\u95ee\u98982\uff1a
\u8fd9\u91cc\u7684\u95ee\u9898\u548c\u4e0a\u9762\u5b8c\u5168\u4e00\u81f4\uff0c\u6240\u4ee5\u697c\u4e3b\u80fd\u628a\u8fd9\u4e24\u4e2a\u95ee\u9898\u6346\u7ed1\u8d77\u6765\u63d0\u95ee\u4e5f\u5f88\u9ad8\u660e\u3002
what\u505a\u8fde\u63a5\u8bcd\u7684\u65f6\u5019\u6c38\u8fdc\u7b49\u4e8e\u201cthe thing(s) that\u201d\uff0c\u90a3\u4e48\u5982\u679c\u7528what\u7684\u8bdd\uff0c\u663e\u7136\u5c31\u662f\u628a\u53e5\u5b50\u5f53\u6210\u5f62\u5f0f\u4e3b\u8bedIT\u5f15\u5bfc\u7684\u53e5\u5b50\uff0c\u800c\u4e0d\u662f\u5f3a\u8c03\u53e5\u4e86\uff0c\u4e8e\u662f\u5b83\u53ef\u4ee5\u628a\u4e3b\u8bed\u8fd8\u539f\uff0c\u53d8\u6210\u201cThe thing that attracted the audience's interest was how the young man had learned five foreign languages.\u201d\uff0c\u800c\u8fd9\u53e5\u8bdd\u663e\u7136\u662f\u6b63\u786e\u7684\u3002
\u4e8e\u662f\uff0c\u95ee\u9898\u53d8\u6210\u4e86\u4e3a\u4ec0\u4e48\u4e00\u5b9a\u8981\u628a\u8fd9\u53e5\u8bdd\u770b\u6210\u5f3a\u8c03\u53e5\uff0c\u800c\u4e0d\u80fd\u628a\u5b83\u5f53\u6210IT\u4f5c\u5f62\u5f0f\u4e3b\u8bed\u5462\uff1f
\u7b54\u6848\u662f\uff0c\u56e0\u4e3a\u5982\u679c\u4e0d\u6389\u8fc7\u6765\uff0c\u8fd9\u53e5\u8bdd\u662f\u9519\u7684\u3002
\u6211\u4eec\u9000\u56de\u4e00\u6b65\uff0c\u7528\u6700\u7b80\u5355\u7684\u65b9\u5f0f\u8fd8\u539f\uff0c\u8fd9\u53e5\u8bdd\u6210\u4e86\u201cIt was how the young man had learned five foreign languages the thing that attracted the audience's interest.\u201d
\u697c\u4e3b\uff0c\u8fd9\u8bdd\u901a\u987a\u5417\uff1f\u662f\u4e0d\u662f\u5f88\u522b\u626d\uff1f\u80fd\u544a\u8bc9\u6211\u522b\u626d\u5728\u54ea\u91cc\u5417\uff1f
\u8fd9\u8bdd\u522b\u626d\u5728\uff0cIT\u4f5c\u5f62\u5f0f\u4e3b\u8bed\u53ea\u80fd\u4ee3\u540d\u8bcd\u6027\u7ed3\u6784\uff08\u4ece\u540d\u8bcd\u6027\u77ed\u8bed\u3001\u52a8\u540d\u8bcd\u3001\u540d\u8bcd\u6027\u4ece\u53e5\uff09\uff0c\u5b83\u4ee3\u4e0d\u4e86\u540d\u8bcd+\u5b9a\u8bed\u4ece\u53e5\u7684\u7ed3\u6784\u3002
\u600e\u4e48\u6539\uff1f
\u5728\u95ee\u98981\u4e2d\uff0c\u6211\u4eec\u6dfb\u4e86\u4e2a\u4e3b\u8bed\uff0c\u628a\u4e3b\u8bed\u4ece\u53e5\u53d8\u6210\u4e86\u5b9a\u8bed\u4ece\u53e5\uff0c\u8fd9\u91cc\u6211\u4eec\u53cd\u5176\u9053\u800c\u884c\u4e4b\uff0c\u7ed9\u5b83\u53bb\u6389\u4e3b\u8bed\u201cthe thing\u201d\uff0c\u628a\u5b9a\u8bed\u4ece\u53e5\u8fd8\u539f\u56de\u4e3b\u8bed\u4ece\u53e5\uff0c\u4e8e\u662f\uff0c\u5f3a\u8c03\u53e5\u7684\u7ed3\u6784\u5c31\u51fa\u73b0\u4e86\u3002
\u6240\u4ee5\u5f52\u6839\u7ed3\u5e95\uff0c\u5f3a\u8c03\u53e5\u548cIT\u4f5c\u5f62\u5f0f\u7684\u4e3b\u8bed\u7684\u533a\u522b\u662f\u4ec0\u4e48\uff1f
\u662fthat/who\u6240\u5f15\u5bfc\u7684\u53e5\u5b50\u662f\u80fd\u591f\u72ec\u7acb\u4f5c\u4e3b\uff0c\u8fd8\u5fc5\u987b\u4fee\u9970\u522b\u4eba\u7684\u533a\u522b\uff1b\u5982\u679c\u80fd\u591f\u72ec\u7acb\u4ece\u5f53\u4e3b\u8bed\u800c\u4e0d\u4f1a\u51fa\u73b0\u903b\u8f91\u9519\u8bef\uff0c\u90a3\u5b83\u5c31\u662fIT\u4f5c\u5f62\u5f0f\u4e3b\u8bed\uff1b\u53cd\u4e4b\uff0c\u5fc5\u987b\u901a\u8fc7\u6dfb\u4e3b\u8bed\u7684\u65b9\u5f0f\u628a\u5b83\u6539\u9020\u6210\u5b9a\u8bed\u4ece\u53e5\uff0c\u8ba9\u5b83\u4fee\u9970\u65b0\u6dfb\u52a0\u7684\u4e3b\u8bed\u53e5\u5b50\u903b\u8f91\u4e0a\u624d\u80fd\u901a\u987a\uff0c\u90a3\u5b83\u5c31\u662f\u5f3a\u8c03\u53e5\u3002
\u4e0d\u77e5\u9053\u6211\u8bf4\u6e05\u695a\u4e86\u6ca1\u6709\uff0c\u6211\u6bd5\u7adf\u4e0d\u662f\u4e13\u4e1a\u7684\u82f1\u8bed\u8001\u5e08\uff0c\u6240\u4ee5\u65e0\u6cd5\u4fdd\u8bc1\u6211\u7684\u8868\u8fbe\u65b9\u5f0f\u80fd\u591f\u6709\u5229\u4e8e\u6c42\u52a9\u8005\u63a5\u53d7\uff0c\u4e0d\u8fc7\u5982\u679c\u8fd8\u662f\u4e0d\u7406\u89e3\uff0c\u53ef\u4ee5HI\u6211\uff1a\uff09
而强调句的结构 it is/was+被强调部分+that/who+句子其余部分，结构词it is/was和that/who都是没有实际意思的，只是构成句子结构的词而已。这个强调句只能强调名词和代词，也就是主语和宾语，不能强调其他句子成分。
你可以对比一下下面两句：
主语从句：It is kind of you to help me with my housework.
强调句：It is you who help me with my housework.
主语从句中it做形式主语的常见句型
常见句型有：
1. It + be + 形容词+主语从句，如：
It is uncertain whether he can come to Jenny’s birthday party or not.
2. It + be + 名词词组 + 主语从句，这类名词有：a fact, a pity, a shame, an honour，a question等，
如：It’s a pity that you missed the exciting football match.
It remains a question whether he will come or not.
3. It + be + 过去分词+ 主语从句，这类过去分词有：announced, believed, expected, hoped, decided, reported, said, shown等，
如：
It is reported that 16 people were killed in the earthquake.
It is not decided who will give the operation to the patient.
it做形式主语 必须用that引导从句吗
不是必须..
it做形式主语，后面内容做句子真正主语，除了由主语从句充当之外，还可以由不定时，不定时短语，动名词以及动名词短语充当，
例如下面句子
It is very useful to learn English so well
It is the police's duty to protect the peope's life and properties
It is not so effective learning English without practising speaking English with others as often as possible
It is his duty taking good care of all his children.
“it”引导主语从句和“it”做形式主语还有强调句型的区别：
it引导的主语从句，形式主语就是it，真正的主语在句子的后面，通常是to do的不定式短语。
而强调句的结构 it is/was+被强调部分+that/who+句子其余部分，结构词it is/was和that/who都是没有实际意思的，只是构成句子结构的词而已。这个强调句只能强调名词和代词，也就是主语和宾语，不能强调其他句子成分。
主语从句：It is kind of you to help me with my housework.
强调句：It is you who help me with my housework.
主语从句中it做形式主语的常见句型：
It + be + 形容词+主语从句，如：It is uncertain whether he can come to Jenny’s birthday party or not.
It + be + 名词词组 + 主语从句，这类名词有：a fact, a pity, a shame, an honour，a question等，如：It’s a pity that you missed the exciting football match.
It remains a question whether he will come or not.It + be + 过去分词+ 主语从句，这类过去分词有：announced, believed, expected, hoped, decided, reported, said, shown等，如：It is reported that 16 people were killed in the earthquake.
额，你所谓的it引导主语从句是说“it 作形式主语的主语从句吧”
那么“it作形式主语的主语从句”和“强调句”的一个最简单的判断方法是把句子的后半部分挪到前面来然后看句子里面有几个动词，有一个就是强调句，两个就是it作形式主语的主语从句
举个例子：
1. It is English that he teaches us.
把后面挪过来为
He teaches us English.
有一个动词 teach，所以为强调句
2. It is interesting that he can teach us English.
那把后面挪过来为
He can teach us English is interesting.
有两个动词 can teach 和 is ，所以为主语从句
另外还有一个不同点是，强调句只能用that，主语从句还可以用别的
有帮助请采纳~不懂欢迎追问~~
it引导的主语从句，形式主语就是it，真正的主语在句子的后面，通常是to do的不定式短语。
而强调句的结构 it is/was+被强调部分+that/who+句子其余部分，结构词it is/was和that/who都是没有实际意思的，只是构成句子结构的词而已。这个强调句只能强调名词和代词，也就是主语和宾语，不能强调其他句子成分。
你可以对比一下下面两句：
主语从句：It is kind of you to help me with my housework.
强调句：It is you who help me with my housework.
选A，这里which后面引导的那是个定语从句，是来修饰山羊的眼睛的。这个句子也是一个强调句。也就是强调句里面有定语从句。
什么是it做形式主语，是用it来代替后面一个冗长的句子，这个冗长的句子才是真正的主语，例如：It
is
very
important
to
study
hard.真正的主语是
to
study
hard，用it代替
to
study
hard
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绛旓細it鍋褰富鐨涓昏浠庡彞濡備笅锛1銆It is difficult for him to give up smoking.2銆両t is a pity to miss the party.3銆両t is kind of you to help me with the problem.4銆両t is no use crying over the spilt milk.5銆両t is no good arguing with him.6銆両t is no pleasure watching ...
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绛旓細濡備笅锛1銆涓昏浠庡彞甯哥敤it浣褰㈠紡涓昏锛屼竴鑸父鐢ㄥ彞鍨嬩负锛It is+{鍚嶈瘝/褰㈠璇/杩囧幓鍒嗚瘝}+涓昏浠庡彞銆2銆佸己璋冨彞鍒欎笉鍚岋紝瀹冪殑缁撴瀯鏄細It+be+琚己璋冮儴鍒+that+浠庡彞銆3銆両t is +鍚嶈瘝+that浠庡彞銆4銆両t is +褰㈠璇+that浠庡彞銆5銆両t +涓嶅強鐗╁姩璇+that浠庡彞銆6銆両t is+杩囧幓鍒嗚瘝+that浠庡彞銆
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绛旓細it 鍋氬舰寮忎富璇鏈変袱绉嶆儏鍐碉細鍙ュ瓙鐨勭湡姝ｄ富璇槸闈炶皳璇姩璇嶏紝鍖呮嫭鍔ㄨ瘝涓嶅畾寮忓拰涓閮ㄥ垎鐗规畩缁撴瀯鐨勫姩鍚嶈瘝鍙ュ紡銆傛鏃剁湡姝ｇ殑涓昏姣斿悗闈㈢殑鈥滅郴琛ㄢ濇垨鈥滆皳瀹锯濇洿闀匡紝涓轰簡骞宠 鍙ュ瓙缁撴瀯锛屾妸涓昏绉诲埌鍚庨潰锛岀敤 it 鏀惧湪鍙ラ鏇夸唬涓昏锛宨t 灏辨槸褰㈠紡涓昏銆傝繖灞炰簬绠鍗曞彞銆傚彞瀛愮殑鐪熸涓昏鏄竴涓彞瀛愶紝姝ゆ椂鐪熸鐨勪富璇瘮鍚庨潰鐨...
