---I was trying to carry out the plan, but I failed.---Well, you , for we were uncertain i

---I was trying to carry out the plan, but I failed.
---Well, you , for we were uncertain it would do .
A. needn’t do that, in fact
B. needn’t have done, in effect
C. needn’t have, in practice
D. needn’t, in time

A. needn’t do that, in factB. needn’t have done, in effect(答案→)C. needn’t have, in practiceD. needn’t, in time解析：第一空考查needn’t have done“本不必做而做了”，第二空填词组in practise“实际上”，句意是：--我想实施计划，但失败了。--你本不必，因为我不确定是否它会付诸实施。因为上文有动词carry out，所以needn’t have done后面的done被省略了。选C。

哦，回答的不错