語態(tài)有兩種：主動(dòng)語態(tài)和被動(dòng)語態(tài)。

主語是動(dòng)作的發(fā)出者為主動(dòng)語態(tài)；主語是動(dòng)作的接受者為被動(dòng)語態(tài)。

1）若賓語補(bǔ)足語是不帶to 的不定式，變?yōu)楸粍?dòng)語態(tài)時(shí)，該不定式前要加"to"。此類動(dòng)詞為感官動(dòng)詞。

feel, hear, help, listen to, look at, make, observe, see, notice, watch

The teacher made me go out of the classroom.

--> I was made to go out of the classroom (by the teacher).

We saw him play football on the playground.

--> He was seen to play football on the playground.

2）情態(tài)動(dòng)詞+ be +過去分詞，構(gòu)成被動(dòng)語態(tài)。

Coal can be used to produce electricity for agriculture and industry.