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).