题干
______time went on, the people in the area came to realize how serious the environment had been polluted.
A：A
B：With
C：Whe
D：While
答案(点此获取答案解析）
A
A：A
B：With
C：Whe
D：While
，现从中有放回地每次取一个球，共
，则
=（ ）