instruction:
Given a scientific passage and an answer, generate a question for the given answer.
question:
Passage: There are three types of mechanical waves. They differ in how they travel through a medium. The three types are transverse, longitudinal, and surface waves. All three types are described in detail below. Answer: three
answer:
How many types of mechanical waves are there?

question:
Passage: Light moving from air into water is bent ___________ the normal. Answer: more
answer:
Light moving from air into water is bent ___________ the normal?

question:
Passage: Vaporization is the process in which a liquid boils and changes to a gas. Answer: gas
answer:
What does liquid change to due to vaporization?