—There is a pen on the ground. Is it Li Long’s?—It Li Long’s. He went to Beijing many days

问题补充：

—There is a pen on the ground. Is it Li Long’s?

—It Li Long’s. He went to Beijing many days ago.

A. can be

B. can’t be

C. must be

D. might be

答案：

A. can be

(答案→)B. can’t be

C. must be

D. might be

解析：can be可能是；can’t be不可能是；must be一定是；might be可能是，表示不太肯定的推测。句意：地上有一支钢笔。是李龙的吗？根据下文，他很多天以前就去北京了。可知前文指的是，这不可能是李龙的。表示肯定的推测，故选B.