用所给单词的适当形式填空。

1. Mary told me that she had been to China ____ (two).

2. Here are the results of the _____ (student) activity survey at Hilltop High School.

3. Can you tell me who is the _____ (healthy) student in your class?

4. My _____ (eat) habits are pretty good.

在光缆接续操作中，下列（）部分无需连通。

A.备用光纤 

B.金属信号线 

C.铠装层 

D.加强构件