act as，act like
乍然看来，act as和 act like是两个同义短语，在涵义上无甚区别可言，其实不然。
act as的意思是“充当”、“担任”，相当于 serve as，可与人或物词如：doctor、director、interpreter、guide、coach、 teacher、go-between、furniture、tools等字搭配使用。as是连词，引导一个省略了谓语的状语从句。例：
this herb can act as an antidote against snakebite．
这种药草可以用作蛇咬的解毒药。
last summer she acted as a guide for tourists．
去年夏天，她担任旅游向导。
this coin may act as a screwdriver