他們都是感官動詞感官動詞有(see,watch,observe,look at, hear, listen to ,notice); 感官動詞有一個重要用法：感官動詞+賓語+do，在用作被動語態(tài)要補出to.例如:I heard her sing an English song just now. She was heard to sing an English song just now. 另外，使役動詞包括(have,let,make)也有這種用法。如： I saw him go upstairs just now. He was seen to go upstairs just nowthanks