Ⅰ. 根据句意及首字母提示，补全单词。
1. Where is the Sahara, the famous d ?
2. China is about 9,600,000 s kilometers in size.
3. It’s very important for everyone to p the environment.
4. It snowed heavily last night. Today there is t snow on the ground.
5. The climbers s in reaching the top of the mountain in the end.
