TASK DEFINITION: You are given a sentence and your task is to generate another sentence that supports the given input.
PROBLEM: The pulmonary arteries carry oxygen-poor blood from the heart to the lungs, and the pulmonary veins transport oxygen-rich blood from the lungs to the heart.

SOLUTION: After the blood in the pulmonary capillaries becomes saturated with oxygen, it leaves the lungs and travels to the heart.

PROBLEM: Consider that human evolution progresses at a very, very slow pace.

SOLUTION: Human evolution shows that evolutionary changes typically occur at a slow pace.

PROBLEM: By convention, no subscript is written when a molecule contains only one atom of an element.

SOLUTION:
If only one atom of a specific type is present a subscript is not used.