That is a very common word but also a word which can confuse people because we can use it in a few different ways.
First we’ll look at two of the ways that we can use it.
1. I know that pilot.
In this example ‘that’ is what we call a determiner, it helps to identify which thing or person you’re talking about. We also use ‘this’, ‘these’ and ‘those’ in a similar way. Note that we use that + noun here.
Let’s look at another example.
2. He said that the mechanic was late.
In this example we use ‘that’ as a conjunction (connecting word) to connect the two other parts together. Here are some verbs which are used in this way; say, agree, deny, suggest, believe, hope, remember, see, hear. Note that in this type of structure we use verb + that + clause
Here are some more examples.
I remembered that I had an exam.
I believed that he was an honest person.
Now try some examples of your own using the two different ways we looked at above.