this kind knife is cutting metal a.used for b.used to c.usedhe has worked in this factory sineit (build)
问题描述：
this kind knife is cutting metal a.used for b.used to c.used
he has worked in this factory sineit (build)
答
used for
因为cutting用的是动名词形式
如果是CUT METAL的话，就可以用used to
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