It is clear that no use can be made

\u6839\u636emake sth clear\uff1bmake it clear that/whether/when\uff1bmake it clear to sb that \u5199\u53e5\u5b50

I am afraid that I didn't (make it clear) what I meant. \u56e0\u4e3adidn't\u540e\u9762\u8981\u8ddf\u52a8\u8bcd\u539f\u5f62\u3002
1\u3001He should make it clear that he has a car.
2\u3001They need to make it clear whether they need you or not.
3\u3001I don't want to make it clear when to go to school.
4\u3001My mom makes it clear to me that if I don't go, she will be very disappointed.

\u5176\u5b9e\u9020\u53e5\u662f\u6700\u7b80\u5355\uff0c\u5148\u628a\u4e2d\u6587\u53e5\u5b50\u60f3\u597d\uff0c\u5c31\u80fd\u7ffb\u8bd1\u51fa\u6765\u4e86\u3002

A.

\u539f\u56e0\u5c31\u662f\u53ea\u6709A\u662f\u5bf9\u7684\u3002\u5176\u4ed6\u7528\u5728\u8fd9\u91cc\u90fd\u4e0d\u5408\u9002\u3002

make use of是一个固定搭配，意思是使用某物，所以第一个空填of；
第二个空表示条件，因为前半句的意思是“我们不能使用镭”，后半句是“我们不清楚它的特性”，可知应该填if。

D. of; if
make use of sth利用某物，固定短语；if 。。。如果。。。

make use of 短语，利用

扩展阅读：xbox series x ... it is high time that ... applied.apple.com ... it is clear that 强调 ... chinesehomemade京东 ... air jordan 1 ... it is obviously that ... witch life story ... as far as i can see ...