语法与词汇
When it was all over, survivors looked at the mess around them and could only standstunned, wondering how the disaster _____.
【正确答案】
A
【答案解析】句意：灾难结束后，幸存者环顾周围的一片废墟，呆呆地站着，想着灾难到底是怎么发生的。由于是灾难发生之后，所以是过去完成时。could have done侧重说能力。would来自于will表示推测，侧重说意愿。