解释一下“一感二听三让四看半帮助”

一感 指的是feel（感觉）二听指的是listen to （听）、hear（听见）三让 指的是let、make、have四看是指watch、see、look、notice、observe半帮助是指help.因为既可以说help sb do sth 亦可以说help sb to do sth 英语中有些动词跟不定式作宾语补足语时省去了to,其中诀是：一感二听三让四观看主动to不见,被动to来见,有些谓语动词主动句中用省to的不定式作宾补,变被动时一定要加上to.例句：1、we heard him sing this song in the classroom.
--> he was heard to sing this song by us in the classroom.2、We often hear her sing this song.
--> She is often heard to sing this song. 3、Let me listen to you sing the song.-->You will be listened to sing the song by me.4、The teacher made me go out of the classroom.
--> I was made to go out of the classroom (by the teacher).5、Tom often makes his sister wash his clothes.
-->Tom’s sister is often made to wash his clothes.
6、We saw him play football on the playground.
--> He was seen to play football on the playground.嘿嘿.就是主动的时候省略to.被动的时候就要加上to.