Match each sentence with the function of the noun clause in bold Direct object, Subject, Predicative nominative, Object of preposition

Even though you didn't bold the noun clauses, it is still obvious which ones they are in these sentences.

1. The noun clause is what I saw in the closet. The function that this noun clause performs is subject. Subject of a sentence is what performs a particular action - in this case, the subject (or the entire noun clause) has left the narrator speechless. If it's confusing, you can replace the clause with a simple pronoun it - It left me speechless, and then it's easier to see it is indeed a subject.

2. The noun clause is how to swim. The function that this noun clause performs is direct object. Direct objects answer the questions whom or what - in this case, you can simply ask - What did I learn when I was six? And the answer would be that entire noun clause - how to swim.

3. The noun clauses here are what my conscience was telling me and what I wanted to do. The function that these noun clauses are performing is object of a preposition. Object of a preposition is really easy to spot - it is a word, phrase, or an entire clause which is located right after a preposition. In this example, the word between is a preposition, and the clauses following it are its objects.

4. The noun clause here is what kept me awake all night. The function that this noun clause performs is predicative nominative. A predicative nominative is a noun, a noun phrase, or a noun clause that is found after a linking verb in a sentence. A linking verb connects two parts of a sentence - here, that verb is is and the clause following it is its nominative.