问题补充:
Having a trip abroad is certainly good for the old couple, but it remains whether they will enjoy it.
A. to see
B. to be seen
C. seeing
D. seen
答案:
A. to see
(答案→)B. to be seen
C. seeing
D. seen
解析:remain 作“尚需”解,是连系动词,其后要接不定式作表语。由于 see 与 it(形式主语,指whether they will enjoy it)是动宾关系,因此用不定式的被动式。