Some basic ideas of the conjunction 'that':
- That as a conjunction is commonly used.
- That introduces that-clauses.
- That-clauses can be the subject or object of a sentence.
- That can be left out but not if it begins a clause.
The conjunction that introduces that-clauses which are subordinate clauses. A subordinate clause cannot stand on its own as a complete sentence.
It is quite likely that we will be late for the firework display.
The part of the above sentence in bold is a that-clause. We cannot use it as a sentence.
Wrong: That we will be late for the firework display.
Wrong because it is a subordinate clause, also is called a dependent clause. It must be joined to a main clause to make a complete sentence. The main clause in the above sentence is It is quite likely.
A that-clause can come at the beginning of a sentence as the subject or at the end of a sentence as the object.
That he got up late does not mean he doesn't have to go to school.
He recalled that he had sent the letter sometime last week.
We can leave out that wherever it may appear in a sentence but not if it is at the beginning.
He said that he would help me with my homework. / He said he would help me with my homework.
It is true that her grandmother is one hundred years old. / It is true her grandmother is one hundred years old.
- That he didn't know anything about it is no excuse. (Not: He didn't know anything about it is no excuse.)
Each is a pair of words which together are used as a conjunction:
1. providing/provided that: on the condition that; if.
- We will be there early providing that we can catch the first train.
- We welcome her to come along provided that she can stay out late.
That in the above two sentences can be omitted.
2. Assuming that: accept as true without proof.
- I think she will marry the wealthy boss's son even assuming that she doesn't love him.
3. Seeing that: because; accepting the fact that.
- You may as well join them, seeing that they need another volunteer.