【题目】Having a trip abroad is certainly good for the old couple, but it remains ______whether they will enjoy it.
A.to see
B.seeing
C.seen
D.to be seen

【答案】D
【解析】句意：去国外旅行对老年夫妻当然是有好处的，但是他们是否能享受旅行还有待考察。remain to be seen 固定短语，”尚不确定，说不准，拭目以待“。故选D。