烃类润滑油中（）的粘温性质最好。
A.烷烃
B.烯烃
C.芳烃
D.二烯烃
参考答案：A
学生刚学英语时，对26个字母的记忆两头容易，中间难，这种现象的解释是 ( )
A．痕迹消退说B．动机说C．同化说D．前摄抑制与倒摄抑制
—_______ we eat in the classroom?
—No, _______. [ ]
A. Can, we can't
B. Can, you can't
C. Do, you didn't
D. Do, they can't
