Words such as and, but, or, nor, for, yet and so can combine clauses or phrases and are called:

Words such as and, but, or, nor, for, yet, and so can combine clauses or phrases and are called conjunctions.
Conjunctions can be coordinating, when they combine to words or independent clauses, or they can be subordinating, when there are subordinate clauses involved.

A: become a alien but sound like a human