They’ve made full preparations, but it remains whether they will be able to do a good job in the experiment.
A. to see
B. seen
C. being seen
D. to be seen
网友回答
A. to see
B. seen
C. being seen
(答案→)D. to be seen
解析：考查不定式的被动做表语：句意：他们已经做好准备了，但是是否在实验中能做得好还又待证实。It remains to be seen whether…，是否…还有待证实，这里不定式的被动做表语，选D。