This document discusses different types of noun clauses and their usage. It covers noun clauses introduced by that, whether, if, what, and wh- words. Some key points include:
- That introduces many noun clauses but can sometimes be omitted. It should never be omitted when introducing a subject noun clause.
- Whether and if are similar and can often be used interchangeably to introduce yes/no noun clauses. Whether or not is also used.
- Embedded questions use statement word order and introduce noun clauses. They can occur within statements or other questions.
- Wh- words like what, when, how introduce embedded wh- noun clauses.