有的不及物动词也有被动语态：Little Bob is too shy to speak if he is spoken to.
主动语态；someone speaks to him.speak + 介词to+宾语,所以很多不及物动词加介词在跟宾语后,也是可以变成被动语态的.
不用被动语态：1.连系动词 look sound smell taste feel appear seem go turn come grow fall asleep
become remain keep stay continue
2 appear =turn up 出现 露面 到达 break out happen occur take place come about
belong to disappear belong to die end(结束） fail succeed sit stand last rise
fit,have,hold,marry,own,wish,cost,notice,watch agree with,arrive at / in,shake hands with,succeed in,suffer from,happen to,take part in,walk into,come true,keep silence,lose heart
3 带同源宾语的及物动词,反身代词,相互代词,不能用于被动语态：
die,death,dream,live,life
She dreamed a bad dream last night.
4.当宾语是不定式时,很少用于被动语态.
(对) She likes to swim.
(错) To swim is liked by her.