Section Ⅳ　Grammar & Writing

　　情态动词(Ⅰ)

　　阅读下列句子，体会黑体部分用法

　　1．Most ancient festivals would celebrate the end of cold weather，planting in spring and harvest in autumn.

　　2．Some festivals are held to honour the dead or to satisfy the ancestors，who might return either to help or to do harm.

　　3．For the Japanese festival Obon，people should go to clean graves and light incense in memory of their ancestors.

　　4．They also light lamps and play music because they think that this will lead the ancestors back to earth.

　　5．Festivals can also be held to honour famous people.

　　1．can与could的用法

　　(1)表示能力(could是过去式)。

　　I can play basketball now，but I couldn't when I was young.

　　现在我会打篮球了，但小时候我不会。

　　(2)表示推测，意为"可能"，一般用于疑问句和否定句(could是过去式)

　　I believe that he can't be so rude.

　　我相信他不会如此粗鲁。

　　(3)表示请求和许可(could表更委婉的语气，回答时只能用can)。

　　Can/Could you lend me a hand？你能帮我一下吗？

　　(4)用于肯定的陈述句中，表示理论上或习惯上的可能性。

　　Accidents can happen at any time.事故随时会发生。

　　[明辨异同]　can/be able to

can 只有现在时和过去时 表示自身具有的能力