1.can
1）表示能力.“能,會(huì)”
Two eyes can see more than one.兩只眼比一只眼看得清.
2）表示允許.“可以”
Can I have a look at your new pen?
我可以看一看你的新鋼筆嗎?
3）表示可能（理論上或是邏輯判斷上）.
A 用于肯定句“有時(shí)會(huì),一時(shí)會(huì)”
The monkeys can be very naughty.
The temperature can fall to –60℃,that is 60℃ below freezing.
氣溫可降至—60℃,也就是零下60℃.
B 用于否定句,疑問(wèn)句
He can’t have enough money for a new car.
他不可能有足夠的錢買新車.
Who can it be?
2.could
1)表示能力,過(guò)去時(shí)間
Could the girl read before she went to school?這女孩上學(xué)前能識(shí)字嗎?
2）表示允許.
過(guò)去時(shí)間He asked whether he could take the book out of the reading—room.
現(xiàn)在時(shí)間的更委婉更客氣的語(yǔ)氣：Could I have one?