That is one of the commonest words in English. It is used in the following ways.
As a demonstrative adjective
As a demonstrative adjective, that is used to point out people or things. It is followed by singular noun.
- Who is that boy?
- Give me that book.
- What was that noise?
As a demonstrative pronoun
That serves as a demonstrative pronoun, when used without a following noun.
- Who gave you that?
- Who said that?
As a conjunction
That is a subordinating conjunction. It can be used to introduce noun clauses, adjective clauses or adverb clauses.
- She told me that she was not coming. (Here that introduces the noun clause ‘she was not coming’.)
- The museum that we visited yesterday was very good. (Here that introduces the adjective (relative) clause ‘we visited yesterday’.)
- We eat that we might live. (Here that introduces the subordinating adverb clause of purpose ‘we might live’.)
The relative pronoun that is often left out when it is the object of the verb in the relative clause. That is not left out in a more formal style.
Study the examples given below.
- Did you receive the parcel? I sent it yesterday.
- Did you receive the parcel that I sent yesterday? (Formal)
- Did you receive the parcel I sent yesterday? (Informal)
Here the relative pronoun that is the object of the verb sent.
That is often left out of expressions like so that and such that.
- I was so excited I couldn’t sleep. (OR I was so excited that I couldn’t sleep.)
That is also used in questions and negatives. In this case, it has a similar meaning to very.
- It wasn’t that bad. (= It was not very bad.)
- There is no need to worry. Her condition isn’t that serious.