You are here


Level: beginner

We use can and can't to talk about someone's skill or general abilities:

She can speak several languages.
He can swim like a fish.
They can't dance very well.

We use can and can't to talk about the ability to do something at a specific time in the present or future:

I can see you.
Help! I can't breathe.

We use could and couldn't to talk about the past:

She could speak several languages.
I couldn't see you.

Ability: can and could 1


Ability: can and could 2


Level: intermediate

We use could have to say that someone had the ability or opportunity to do something, but did not do it:

She could have learned Swahili, but she didn't want to.
I could have danced all night. [but I didn’t]

Ability: could have 1


Ability: could have 2



I am struggling to understand the use of modal verbs in the following situation. The situation is I am having a chat with someone about a friend's mother who was to arrive to the city I live in last week. Here are the three ways that I thought this could be conveyed but i would really appreciate your guidance.
1) She must have arrived now 2) She will have arrived now 3) She should have arrived now.
In the situation that I have provided, which of the above three sentences is most appropriate to use and if all three can be used then what is the difference among them?
Thank you so much.

Hello autumn,

All three sentences are possible and I'm afraid it's not possible for me to say which is correct without knowing how you see the situation. In addition, modal verbs have different uses and so can be used to convey different ideas.

That said, in general, 'must have arrived' suggests you strongly believe, 'will have arrived' expresses much the same idea, suggesting it would be unusual if not, and 'should have arrived' suggests much the same thing, i.e. that she will be there unless something unusual has happened.

By the way, in all three sentences I'd suggest 'by now' instead of 'now'.

All the best,
The LearnEnglish Team

Hi Teachers,

Is it "May I know who you are ?" or "May I know who are you?"?



Hello Tim,

The first one is correct. It is a reported question and therefore has this word order.

All the best,
The LearnEnglish Team

Hello dipakrgandhi

'May I know who are you?' is not correct in standard British English; instead, it would be 'May I know who you are?'.

Even though this is more of a request or polite command, it has the structure of a reported question.

All the best


The LearnEnglish Team

Hello Tim,

Yes, you're right! Sorry for the confusion. Reported and indirect questions follow the same word order.

All the best,
The LearnEnglish Team

Thank you , I think , it is good to refresh our knowledge through a fun exercise.
All the best,


You mentioned above that "We use conditionals to give advice: Dan will help you if you ask him" and that "Past tenses are more polite: Dan would help you if you asked him". But aren't these the structures of the first and second conditionals respectively? In order words, regarding the second sentence which utilises the past tense, isn't it done so as to express the second conditional (•if + past simple, ...would + infinitive), rather than for politeness?

Appreciate your advice, thanks!


Hi Timothy555,

Second conditional forms are used to describe less likely events and one way to make a request or advice polite is to make it more tentative. Using a hypothetical form is one way to do this. In other words, the fact that it is a second conditional form and that it is a polite form are not mutually exclusive.


Best wishes,


The LearnEnglish Team

"you mustn't make a noise " it's says at the example above ,i'd like to know why we didn't use can't instead of mustn't and what's the difference and why at school in London they thought us that the negative form of must is can't not mustn't.