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.

[Q]: Question: Where does chemical digestion mainly occur? Answer: small intestine
[A]: Chemical digestion mainly occurs in the small intestine.


[Q]: Question: Secondary pollutants form from chemical reactions that occur when pollution is exposed to what? Answer: sunlight
[A]: Secondary pollutants form from chemical reactions that occur when pollution is exposed to sunlight.


[Q]: Question: Skeletal muscles must work in pairs to move bones back and forth at a joint because they can only do what? Answer: contract
[A]:
Skeletal muscles must work in pairs to move bones back and forth at a joint because they can only contract.