根据句意及首字母提示补全单词。

1. We should learn from the space h_____, Yang Liwei.

2. He has p_____ his courage in the battle.

3. I'm afraid the m_____ is away on business.

4. For i_____, the less exercise you take, the fatter you will be.

5. Germs are so t_____ that we can only see them by microscope (显微镜).

建筑物的经过年数有实际经过年数和有效经过年数，它们之间关系为（）。

A.有效经过年数等于实际经过年数

B.有效经过年数短于实际经过年数

C.有效经过年数长于实际经过年数

D.有效经过年数可能长于或短于实际经过年数