Jim was not _________ to the club, because at that time he was not a member of it.

A．allowed

B．permitted

C．admitted

D．promoted

下列关于水提醇沉法操作的陈述，错误的是（）

A.水提液必须浓缩后再加乙醇处理

B.尽可能采用减压低温浓缩法

C.浓缩前后可视情况调整pH值

D.浓缩程度应根据成分性质决定

E.应将浓缩液慢慢加到乙醇中