What kind of sentence is this.

As Harry walk to school, he whistled his favorite song.

This sentence is a simple sentence.

The sentence "As Harry walked to school, he whistled his favorite song" is a complex sentence.

The sentence "As Harry walked to school, he whistled his favorite song" is a complex sentence.

To determine the type of sentence, we need to analyze its structure. A complex sentence consists of an independent clause and at least one dependent clause. In this sentence, "He whistled his favorite song" is an independent clause because it can stand alone as a complete sentence. On the other hand, "As Harry walked to school" is a dependent clause because it cannot stand alone as a complete sentence and relies on the independent clause to make sense.

The presence of the dependent clause "As Harry walked to school" at the beginning of the sentence introduces additional information about when or how Harry whistled his favorite song. This dependent clause adds complexity to the sentence structure, making it a complex sentence.