欲将蛋白质从水溶液中析出而又不改变蛋白质的性质，应加入的试剂是[ ]

A．NaOH溶液

B．(NH₄)₂SO₄溶液

C．CuSO₄溶液

D．酒精溶液

People try to avoid public transportation delays by using their own cars,and this          creates further

problems.[ ]

A.in short

B.in case

C.in doubt

D.in turn