Introduction to noun clauses

A noun clause is a group of words that contains a subject and a verb. It acts as a noun. Note that a noun clause cannot stand alone. It is a subordinate clause and it needs to be attached to an independent clause.
A noun clause can be the subject or object of the verb in the main clause.
Study the examples given below.

What you said was not right.

Here the noun clause ‘what you said’ acts as the subject of the verb was.
Another example is given below.

What she did was to let out a scream.

Here the noun clause ‘what she did’ acts as the subject of the verb was.
In the following examples, the noun clause acts as the object.

I don’t know what she thinks.

Here the noun clause ‘what she thinks’ acts as the object of the verb know.

She said that she would come.

Here the noun clause ‘that she would come’ acts as the object of the verb said.
A noun clause can begin with a question word.
The clauses given below are all examples of noun clauses.

where she lives

what I think

how she makes a living

who he is

what his name is

Do you know where she lives?

I don’t know how she makes a living?

Do you know who he is?

Do you know what his name is?

A noun clause can begin with the conjunction if or whether.

I don’t know if I will have time.

I don’t know if I will pass.

I don’t know whether he will recognize me.

A noun clause can begin with ‘that’.

She said that she would come.

He said that he didn’t know the answer.

A noun clause can begin with a question word + to-infinitive.
I don’t know what to say. (= I don’t know what I should say