, the experiment is sure to succeed.
A. If carefully doing
B. If carefully done
C. If it done carefully
D. If it doing carefully
网友回答
A. If carefully doing
(答案→)B. If carefully done
C. If it done carefully
D. If it doing carefully
解析：
试题分析:考查非谓语动词。从四个选项可知，此题考查非谓语做状语，动词do和句子主语experiment之间是被动关系，所以排除A、D选项。而C选项中有主语但是谓语不完整，故B选项正确。属于连词+分词形式，此处也可以看做是if it is carefully done的省略。句意：如果认真做的话，这个实验肯定能成功。