介绍:
重点内容：
1. what do you say ?
2.scenery
3. stream
4. trail
5.steep
6.in an emergency
7. to be prepared
8.insect protection
9.planet
10.sun screen
11. That makes sense.
12.be likely to
13.flashlight
14.torch
15. natural
16. depend on
17. half a liter
