问题补充:
It was not a good idea to go skating. You your leg.
A. can break
B. could break
C. could have broken
D. could have been broken
答案:
A. can break
B. could break
(答案→)C. could have broken
D. could have been broken
解析:本题关键为抓住题中提供的信息。“It was not a good idea’表明动作发生于过去,情态动词后接动词完成式表明对过去动作的猜测。