感官动词及使役动词(如：see, feel, hear, watch, make, bid)在主动语态中用无to不定式作宾补，改为被动语态时不定式前要加to

　　例1 Because of many mistakes, she was made _____ these letters again.

　　A.tape B.to typing C.typed D.to type

　　【答案】D本句的意思是：因为错误太多，她又把字重新打了一遍。