属于阳离子型表面活性剂的是（）
A.卵磷脂
B.度米芬
C.Tweens
D.卖泽
E.洁尔灭
参考答案：B, E
Questions 23-26
A．By taking notes.
B．By remembering what was said.
C．By getting up to shut the door.
D．By asking questions.
DES的密钥长度为( )。
A．32bit B．48bitC．64bit D．128bit
