An object clause with what as the leading word

What is the subject in the first sentence? Just follow the predicate without changing the sentence pattern.

Do you know his address?

What is the object in the second sentence? "What's his address? What is his address? ) ",so change the word order.

When what is used as a guide word, what acts as a sentence component, so it depends on whether the clause lacks what as a component, such as subject, object and predicate.

Extended data:

As a leading word, only what is the matter and what is wrong are the object clauses, because in these two cases, what is both a leading word and a subject, and in other cases, the word order must be changed.

What object clauses are divided into three categories:

Tenses of object clauses of verbs, prepositions and adjectives;

1 The main clause is the simple present tense, and the clause can be at any time. ?

2. Use the past tense in the main sentence and the past tense in the clauses. ?

3. When the main clause is used and the subordinate clause is true, only the simple present tense is used.