蛋白质盐析
参考答案：
当盐浓度达到一定范围时，蛋白质溶解度随盐浓度的增加而降低并从溶液中析出，该技术称为蛋白质盐析。
It was because of the bad weather ______ the sports meet was put off.
A．when
B．which
C．where
D．that
Do you _________ a dog _______ a pet athome![ ]
A. have, as
B. keep; for
C. keep; as
D. both A and C
