在横线上填入所缺部分，使句子完整（注意：每空不止一个单词）。

1. Unless you go along the river , you ________________________________ ( 迷路) in the forest.

2. ________________________________ ( 减少空气污染) is everyone’s duty.

3.The book Tiny Times written by Guo Jingming ________________________________ ( 值得一读).

4.----I called you just now , but got no answer.

  ---- Sorry。 I________________________________ ( 发送电子邮件)in the library then.

5. I think this journey is ________________________________ ( 最愉快的经历).