Can vs Could: How to Use the
我们来讨论一下情态动词can和could的用法。我们都知道能用英语表达做某事的能力或可能性有多重要，但英语语法可能很棘手。
而an和could是情态助动词，用来表达一种能力、许可、请求、提供或机会。在本文中，我们将探讨can和could之间的区别，以及如何使用它们。
Can vs. Could: 使用规则
Could 是Can的过去式
动词could主要是can的过去式。但它不仅仅是can的过去式:它还有其他can不具备的功能，例如，在第一件句中，参见英语条件从句的使用
例句
- She can speak Italian very well.
- I could swim, but I couldn’t ride a bike when I was nine years old.
- You can play with Amy after you do your homework.
- Could I have some tea?
- Can I carry your bags?
- We could go somewhere tonight.
- That can’t be true.
- You could get there in time if you hurried up.
表达感知动词的能力
Can和could也可以用来表示感知动词(看、听、感觉、味道、嗅觉等)的连续时态，以及理解、记住等动词。这些词分别是(see, hear, feel, taste, smell, like understand, remember)等。
例句
- Can you see the light over there?
- When I entered the room, I could hear something scratching.
- Harry put the keys in his pocket, but now he can’t find them.
- We couldn’t understand what the stranger was saying.
表面一般的能力
作为动词can的过去式，could在过去式和间接引语中用来表达一般能力。
例句:
- He said he could get that ticket for me.
- When I was younger, I could work out for two hours without stopping.
命令或要求某事
在请求、命令和句子中，使用could比can更礼貌。
例句：
- Do you think you could help me with this case?
- Can I use your phone?
- Could you do me a favour?
- Do the urgent task first, and then you can check the rest.
请求允许
当然，当我们请求许可时，最好使用动词can，因为could不能用来表示同意或拒绝同意
例句：
- Can I trust you? – Of course, you can.
- You can stay here if you want to.
- Can I have another cup of coffee? – No, I’m afraid you can’t.
You drank too much coffee.
