You are given a sentence and your task is to generate another sentence that supports the given input.

Example input: In spite of this reduced heat input, the surface temperature of Venus is higher than that of the Earth.
Example output: Venus has a warmer average surface temperature than earth.
Example explanation: Output statement supports the input statement's claim about the temperatures of Venus being higher than the earth.
Q: Backflow of blood in the heart is prevented by four valves made of flaps of connective tissue.
A:
Heart valves prevent the backflow of blood from happening in the heart.