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）
小题1:Unless you go along the river , you _____________________( 迷路) in the forest.
小题2:_____________________________________________( 减少空气污染) is everyone’s duty.
小题3:The book Tiny Times written by Guo Jingming ________________________________( 值得一读).
小题4:----I called you just now , but got no answer.
---- Sorry。 I_____________________________________( 发送电子邮件)in the library then.
小题5:I think this journey is _________________________________________( 最愉快的经历).
