题目内容：

this kind knife is cutting metal a.used for b.used to c.used
he has worked in this factory sineit (build)

优质解答

选a 因为be used to doing意思是习惯于做某事,而在这句话里,正确的意思是＂被用来做某事＂所以不能选b．use是不及物动词,后面如果有动词,动词前必须加介词,所以不能选c