I must be going 请教一个简单的英语问题

I must go\u4e0eI must be going \u6709\u4ec0\u4e48\u533a\u522b

go \u662f\u4e00\u79cd\u77ac\u95f4\u7684\u8d8b\u5411\u884c\u4e3a.go\u4ec5\u4ec5\u8868\u793a\u4f5c\u51fa\u201c\u79bb\u53bb\u201d\u7684\u52a8\u4f5c,\u800c\u8d8b\u5411\u52a8\u8bcd\u7684\u8fdb\u884c\u65f6\u6001\u5219\u8868\u793a\u201c\u6b63\u51c6\u5907\u4f5c\u51fa\u4e00\u79cd\u77ac\u95f4\u884c\u4e3a\u201d,\u56e0\u6b64 be going \u7684\u610f\u601d\u5219\u662f\u201c\u8981\u8d70\u800c\u6ca1\u6709\u8d70\u201d\u7684\u52a8\u4f5c,\u4e5f\u5c31\u662f\u51c6\u5907\u8981\u52a8\u8eab.
\u53e6\u5982\uff1a
He leaves homefor school at six every day.\u4ed6\u6bcf\u5929\u516d\u70b9\u79bb\u5f00\u5bb6\u4e0a\u5b66.
He is leavingfor school in a few minutes.\u4ed6\u8fc7\u4e00\u4f1a\u5c31\u8981\u79bb\u5f00\u5bb6\u4e0a\u5b66.
Spring comesafter winter.\u51ac\u5929\u8fc7\u540e\u6625\u5929\u5c31\u5230\u4e86.
Spring is comingafter winter.\u51ac\u5929\u8fc7\u540e,\u6625\u5929\u5c31\u8981\u5230\u4e86.
\u53ea\u8981\u638c\u63e1\u8d8b\u5411\u52a8\u8bcd\u8fdb\u884c\u65f6\u6001\u7684\u8fd9\u4e00\u7279\u70b9,\u5c31\u4f1a\u77e5\u9053I must go \u7684\u610f\u601d\u662f\u201c\u6211\u5fc5\u987b\u9a6c\u4e0a\u79bb\u5f00\u201d,I must be going \u7684\u610f\u601d\u5219\u662f\u201c\u6211\u5fc5\u987b\u505a\u597d\u79bb\u5f00\u7684\u51c6\u5907\u201d.

i'm afraid \u672c\u8eab\u53ef\u4ee5\u5f15\u5bfc\u865a\u62df\u8bed\u6c14\u3002
must go\u662f\u5f3a\u8c03\u72b6\u6001\uff0c\u5fc5\u987b\u8d70\u3002
must be going\u662fmust do\u548cbe doing\u7684\u7ed3\u5408\uff0c\u8fd9\u91cc\u53ef\u4ee5\u7406\u89e3\u4e3a\u5fc5\u987b\u8981\u2026\u2026\u7684\u72b6\u6001

这句话中主语是I谓语是must be going. 我必须得走了。用的是情态动词十进行吋态，这里表将来。Thanks for treating us We must be going now.

going 是现在分词 是谓语形式的一部分 和 must be 一起构成谓语
主语是I
没有宾语

I主 must be going谓
must be doing情态动词+进行时
我得走了

扩展阅读：i got smoke acfun ... invite sb to do sth ... it is no use doing ... i just wanna kiss you ... this war of mine ... show you around ... see you soon ... mbt ... welcome you to do ...