不定式和动词-ing形式的被动语态
请看两道试题：
1. 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
分析：remain 后接to do sth.作表语， see 与主语从句是动宾关系，所以要用to be seen，故答案为B。
2. The discovery of new evidence led to ______.
A. the thief having caught B. catch the thief
C. the thief being caught D. the thief to be caught
分析：lead to 中的to 是介词，后接动词-ing形式作宾语。“小偷被抓”应用动词-ing的被动形式being caught，所以选C。
