What are nitrates used for?（ ）.
A.正确答案BThey preserve flavor in packaged foods
B.They preserve the color of meats
C.They are the objects of research
D.They cause the animals to become fatter
What are nitrates used for?（ ）.
What are nitrates used for?（ ）.
A.正确答案BThey preserve flavor in packaged foods
B.They preserve the color of meats
C.They are the objects of research
D.They cause the animals to become fatter
