I. 根据首字母提示或中文提示补全单词：
1. His s_________ is still uncertain; he has been very badly hurt and may die.
2. I held an important p____________ with the company.
3. Q_________ is more important than quantity.
4. Failure is mother of s___________.
5. It was very dirty, but he m____________ to clean it.
6. What do you know about Yang Liwei and his life before he became a world-famous ___________ (宇航员)？
