When you start studying in advance, you have time to ask your teacher questions; therefore, you usually score higher on the test.

Simple
Compound
Complex
Compound-Complex

1 answer

The sentence you provided is a complex sentence. It contains an independent clause ("you usually score higher on the test") and a dependent clause ("When you start studying in advance, you have time to ask your teacher questions"). The dependent clause cannot stand alone as a complete sentence and is connected to the independent clause.