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.

[EX Q]: Question: What can be used to determine the mass of a quantity of material? Answer: molar masses
[EX A]: Molar masses can be used to determine the mass of a quantity of material.

[EX Q]: Question: What do concentric circles on a topographic map indicate? Answer: a hill
[EX A]: A hill do concentric circles on a topographic map indicate.

[EX Q]: Question: After an infection has been brought under control and most cytotoxic t cells die off, a few remain as what? Answer: memory cells
[EX A]:
After an infection has been brought under control and most cytotoxic t cells die off, a few remain as memory cells.