Which of the following is not a simple sentence?

Concept

The number of clauses in a sentence decides its type. A clause is a word-group with its own subject and finite verb. A simple sentence has exactly one independent clause and no subordinate clause. A complex sentence has one independent clause plus at least one subordinate (dependent) clause. The key test: a phrase (for example a prepositional phrase) has no subject–verb pair and never makes a sentence non-simple; a subordinate clause does.

Applying the test to each sentence

1. "She reads what she likes." — main clause "She reads," and "what she likes" has its own subject "she" and verb "likes," so it is a clause, not a phrase. It serves as a noun clause (the object of "reads") and depends on the main clause. One independent + one subordinate clause = complex sentence — so this is the sentence that is not simple.

2. "I have a very costly book in my house." — single core "I have"; "in my house" is a prepositional phrase (no subject–verb of its own). One independent clause only → simple sentence.

3. "She does not know good manners." — single core "She does not know"; "good manners" is the object. Negation does not add a clause. One independent clause only → simple sentence.

4. "He is a man of great knowledge." — single core "He is a man"; "of great knowledge" is a prepositional phrase modifying "man." One independent clause only → simple sentence.

Why the answer holds

Three of the four sentences extend their single clause only with phrases, which never break the one-clause rule, so they stay simple. Only "She reads what she likes." adds a second, dependent clause ("what she likes"), which makes it complex. Therefore the sentence that is not a simple sentence is "She reads what she likes."

Quick reference

• Simple: one independent clause — e.g. "He plays cricket."

• Complex: one independent + at least one dependent clause — e.g. "He plays cricket because he enjoys it."

• Compound: two or more independent clauses — e.g. "He plays cricket and she plays tennis."