Question

Perce Blackborow and his companions stayed on Elephant Island for six months before rescue came, so they ________ a lot of difficulties.

A．must go through	B．may go through
C．must have gone through	D．could have gone through

Answer 1

C

考查情态动词。根据题意可知本句为对过去事情的推测，故用情态动词+ have done，根据句意可知must have done过去一定做某事，选C。