can和could是我们最常用来表达”可以“的意思,而且之前的文章有讲过can和could分别是使用于现在时态和过去时态,那除了这两点,是否还有其他区别?它们和be able to 又有什么关系?
Can
我们用can表达事情是可能的,或者某人有能力做某件事情。表达的结构为:
can+动词(can do/ see/ eat......)
我们可以从客厅看见那个公园。
He can speak four languages.他可以说四种语言。
有时候我们也会用be able to 表示”可以“,但是can 更常用一些,不过在现在完成时中,都是用be able to 来表示。
Tom 无法入睡。
Tom 无法入睡。
Tom haven't been able to sleep recently.(现在完成时态)Tom最近无法入睡。
Can的否定形式是:can not/ can't,表示”不能“。
I can't come to the party on Saturday.周六的派对我去不了。
同样,can't 也可以表示”觉得某事不可能“
You can't be hungry, you've just had lunch.你不可能饿了,你才刚吃完午饭。
而表示”确定某事是真的“,则使用must。
Mike: Oh, it must be very noisy.(噢~那肯定很吵)
Could
之前有讲过,could是can 的过去时态,用于过去式的句子中,同样表示”可以“。它经常跟see,hear,smell,taste,feel,remember,understand一起使用:
He spoke in a very low voice, but I could still understand what he said.他用很小的声音说话,但是我还是能够明白他的意思。
When we went into the house, we could smell the buring from the kitchen.当我们走进房间的时候,可以闻到从厨房传来的烧焦味。
除了作can的过去式使用,could也可以表示”可能“,类似于may/ might。
The phone is ringing, it could be Jill.=The phone is ringing, it may/ might be Jill.
电话响了,可能是Jill打来的。
The weather is nice now, but it could change later.=The weather is nice now, but it may/ might change later.
现在天气很不错,但是一会可能会变天。
但是,couldn't 是不同于may not和might not的。
She couldn't have seen you, because she was too far away.她不可能看到你,因为距离太远了。
She might not have seen you.她可能没有看到你。
疑问句中的Can/ Could/ Would...?
在表达”请求“”提出要求“”许可“”邀请“的问句,通常分别使用Can,Could,Would。
请求别人做某事时,经常使用can或者could:
I wonder if you could help me.Can/ Could you wait a moment, please?Can you do me a favour?Could you tell me how to get to the station?想要某些东西的时候,可以使用Can I have.../ Could I have...:
Can I have these stamps, please?我可以拿这些邮票吗?
Could I have a cup of tea, please.我想要一杯茶
在请求许可时,可以使用 Can,Could,May:
Can I speak to Tom, please?May I come in? --Yes, please.允许别人做某事时,最常用Can:
Yes, you can use the phone.是的,你可以用这部电话。
主动提出想要做某事时,可以用Can I...?:
Can I help you?Can I give you something to drink?邀请别人时,我们可以用Would you like...?:
Would you like to come to dinner tonight?--"Yes, I'd love to."