【重点单词】tired adj.疲倦的，疲劳的['tad]I feel so tired. Let's have a rest!我觉得很累。让我们休息一下吧!cause v.使发生，引起，导致n.原因，起因[kz]What is the cause of this?这是什么原因呢?litter n.废弃物，垃圾v.乱丢杂物 ['lt]Littering is a bad behavior.乱

Unit 4 Finding your way一、重点词组、句型1. Are you sure, Hobo?be sure of sth. 对……确信（有把握）be sure to do sth. 一定要去做某事be sure +that从句I am sure of my answers.我对我的答案有把握。They are sure to win the game.他们一定会赢得比赛。I am sure th