the experiment will be successful. A. If carefully doingB. If it done carefullyC. If car

问题补充：

, the experiment will be successful.

A. If carefully doing

B. If it done carefully

C. If carefully done

D. If doing carefully

答案：

A. If carefully doing

B. If it done carefully

(答案→)C. If carefully done

D. If doing carefully

解析：考查省略。在if引导的条件状语从句中，省略了主语和be动词，experiment与do之间是被动关系要用被动语态，即完整句子应该是，If the experiment is done carefully。所以答案选C。