ket語(yǔ)法考試：could you please open the door

1. 過(guò)去進(jìn)行時(shí)

用來(lái)談?wù)撨^(guò)去某一時(shí)間正在發(fā)生的事情。

I was playing football at 3:30 yesterday.

用來(lái)討論過(guò)去某一時(shí)間同時(shí)發(fā)生的兩件事

He was doing homework while his sister was watching TV.

過(guò)去的情況和過(guò)去的情況發(fā)生在同一句話中：

Iwas doing homework when mysister cameto talk to me.

Someone knocked at the doorwhilemy mother was cooking.

否定句，疑問(wèn)句的表達(dá)方式：

He was not/wasn't working.

They were not/weren't speaking to each other.

Was he working?Yes, he was/No, he wasn't.

Were they speaking to each other? Yes, they were/No, they weren't.

2. can/can't/could/couldn't

有時(shí)，could可用作can的過(guò)去式。

can/can't表達(dá)能力，用于當(dāng)今時(shí)代。

I canhelp you.(我可以幫助你)

could/couldn“t表示能力，在過(guò)去使用。比較：

can/can't表示概率，用于當(dāng)今時(shí)代。

This can't be true.(這個(gè)不可能是真的)

could表示概率，用于過(guò)去，或者用于現(xiàn)在，但是語(yǔ)氣不如can強(qiáng)烈。

He couldn't go therewithout me.(他不可能不帶我一起去)

can/could也可用于當(dāng)今時(shí)代的請(qǐng)求，不同之處在于could比can語(yǔ)氣更加委婉客套。

Can you help me please?

Could you please open the door?