TASK DEFINITION: In this task, you are given a question and an answer, you would be asked to create the sentence based on the Question-Answer provided. It should be contained within the Question-Answer provided.
PROBLEM: Question: What do craters and rifts become when they fill with water? Answer: lakes

SOLUTION: Lakes do craters and rifts become when they fill with water.

PROBLEM: Question: What is the term for daily cycles of behavior, like the sleep-wake cycle? Answer: circadian rhythms

SOLUTION: Circadian rhythms is the term for daily cycles of behavior, like the sleep-wake cycle.

PROBLEM: Question: What causes a voltage to exist across the membrane in cells? Answer: difference in charges

SOLUTION:
Difference in charges causes a voltage to exist across the membrane in cells.