could 和 be able to 问题
It could only get over the mountains if it rose to 10000 feet.
This means it _________ over the mountains.
A.would succeed in getting
B.got
C.was able to get
D.had got
应选哪个?请说明原因。
为什么不选C?
参考答案:答案是 A.would succeed in getting 。虚拟语气。
虚拟条件句的主句中不能缺少would,should,might或could。
was able to get改为would be able to get也可以。