—I saw Helen in the library this morning.

—No, it ______ her. She moved to France last week.   [ ]

A. can't be          

B. can be          

C. mustn't be

横越停留列车时，严禁钻车，必须从车钩上、车门处越过或在停留车（）以外绕过，并要防止提开车钩，注意临线来车。

A、3m

B、4m

C、5m

D、6m