Question

Taking a trip abroad is certainly good for old couples, but it remains ____ whether they will enjoy it.

A．to see

B．to be seeing

C．to have seen

D．to be seen

Answer 1

D

试题分析：句意：去国外旅行对这对老夫妻是好的，但是否他们喜欢还有待以后再看。这里it是形式主语，whether they will enjoy it是真正的主语从句，这里it与see之间是被动关系，故选D。
点评：本题难度适中。做这题需要解析句子结构，确定设空在句子中充当的功能（如状语、定语或宾补）；找准相关动词的逻辑主语，确定该动词与逻辑主语是什么关系（主动还是被动）。
即学即练：Dinosaurs have completely died out on the earth，never _________ again.
A. to be seen             B. being seen
C. seen                   D. having been seen
解析：A。句意：结果再也没有人见过。