Wh-words are what, when, where, who, which, why and how.

We use clauses with a wh- word:

  • In wh-questions (see Questions and Negatives):

What are you doing?
Who ate all the pies?
Why did you do that?

  • after verbs of thinking:

know - understand - suppose - remember - forget - wonder

I know where you live.
She couldn’t remember who he was.
John wondered what was going to happen next.

NOTE: We also use clauses with if

I wonder if we’ll see Peter.
She couldn’t remember if she had posted the letter.

  •  after verbs of saying:

ask - say - admit - argue - reply - agree - mention - explain - suggest

I asked what she wanted.
He tried to explain how the accident had happened.
She wouldn’t admit what she had done.
Did he say when he would come?

tell and some other verbs of saying must always have a direct object (see clauses, sentences and phrases):

tell - remind

We tried to tell them what they should do.
She reminded me where I had left the car.

  • after some verbs of thinking and saying we use wh-words and the to-infinitive:

We didn’t know what to do.
We will ask when to set off.
Nobody told me what to do.
Can anyone suggest where to go for lunch?

NOTE: We use the to-infinitive:

-- When the subject of the to-infinitive is the same as the subject of the main verb:

He didn’t know what to do >>> He didn’t know what he should do
We will ask when to set off >>> We will ask when we should set off

-- When the subject of the to-infinitive is the same as the person spoken to:

Nobody told me what to do. >>> Nobody told me what I should do.
Can anyone suggest where to go for lunch? >>> Can anyone suggest [to us] where we should go for lunch.

  • after some nouns to say more about the noun:

Is there any reason why I should stay?.
Do you remember the day when we went to Edinburgh.
That was the town where I grew up.

We often use a wh-clause after is:

I missed my bus. That’s why I was late.
This is where I live.
That’s what I thought.
Paris – that’s where we are going for our holidays.




hi kirk

thank you so much for your appreciating.

Hi, please help me with this exercise.

"Famers work on their farm from morning till night."

Make question with the phrase "from morning till night", I have a big confusion between "when" and "how long". So which one is the best choice? Thanks a lot

Hi Kelvin Dao,

I'm afraid we don't provide answers for tasks which are not from our pages - if we tried then we would be doing people's homework for them and would never have time for anything else! However, I can help you with the difference between these two words.

We use how long when we are asking about duration.

We use what time or what day when we are asking about a clock time or calendar date.

We normally use when in a similar way to what time or what day - when we are asking about a clock time or calendar date - but it can also be used to ask about duration in some contexts.

When is the most general word (phrase) of the three.


Best wishes,


The LearnEnglish Team

hi, sir
please clear my doubt.
where are you inserting the pen-drive?
i am inserting the pen-drive into computer.
is this right? or
i am inserting the pen-drive at my office.
which one is right please tell me.
and explain

Hi Afia shakir khan,

The sentence

I am inserting the pen-drive into computer.

is correct and describes how you use the pen-drive. The second sentence tells us not about the pen-drive and its use, but about you and your location. It is a perfectly grammatical sentence, but it tells us about you and where you are, not about the pen-drive. As an answer to the question you give, it does not work.


Best wishes,


The LearnEnglish Team


I would like to know if these question is correct:

"Who did you think to invite to the party?

Tks a lot,

Hello Mariana,

That question is grammatically correct, though I'd need to know the situation and understand what you want to say in order to tell you if it communicates your ideas correctly or not. 

All the best,
The LearnEnglish Team

Hello Peter,

I got it. Thank you very much.



One of the last point says using wh-clause after some nouns to give information about the noun. I was wondering whether "that" and "which" can do the same job here?

For example, are there any differences in below sentences?
1) This is the table where the legs are yellow
2) This is the table that the legs are yellow
3) This is the table which the legs are yellow

What I want to know is whether the "where, that and which" are doing the same functions as giving more information to the noun ie table here? If they are the same, are there any differences in meaning between the sentences?


Hello Hugo,

Yes, you could use 'that' or 'which' in a similar sentence, e.g. 'Is that the bus that goes to Manchester?'. You could also 'which' instead of 'that' and there'd be no difference in meaning.

By the way, the three sentences you wrote are not correct – 'that' needs to be followed by a verb and complement in 2 and 3. I'd recommend something like 'This is the table that has yellow legs' as an alternative.

All the best,
The LearnEnglish Team