Clauses beginning with that are common in English. There are two distinct types of “that” clauses.
In the first type, that is a relative pronoun. In relative clauses, that refers to a noun antecedent. The entire “that” relative clause is an adjective describing the noun antecedent.
- Those flowers that she gave you smell wonderful. (antecedent = flowers)
- The trees that grow in this forest are thousands of years old. (antecedent = trees)
In the second type of “that” clause, that is not a relative pronoun because it does not replace a noun. Instead, the entire “that” clause itself is a noun. Typically, these “that” noun clauses follow verbs of communication, such as tell, say, and report, and verbs of thought or emotion, such as forget, remember, think, learn, know, discover, hope, fear, and believe.
- She said that she would be late.
- Lori forgot that the meeting had been canceled.
- The engineers believed that they could design a better car.
Whenever that is not the subject of a clause, it can be omitted.
- The engineers believed they could design a better car.
In the examples above, the “that” noun clause is the object of the verb. “That” noun clauses can also be subjects.
- That he expressed no remorse for his crimes turned the jury against him.
- That they were able to accomplish so much surprised their critics.