消费者从物品消费中所获得的总效用一定是不断增加的，边际效用总是正的。

厚度等于或小于的钢板，按张数的10%行（）检查。

A．超声波

B．力学性能

C．磁粉探伤

D．射线

以下（）是保安员的禁止性行为。

A.搜查他人身体

B.查验出入人员证件

C.登记出入车辆

D.设立临时隔离区

—I called you last night, but nobody answered.

—I _______ dinner with my family in the restaurant.[ ]

A. have

B. had

C. have had

D. was having

用冠词a/ an或Be动词（am / is / are ）填空。

小题1:What’s this in English ?  It’s ________ pen.

小题2:Is that _________ orange?  No, it isn’t.

小题3:It is ________ ruler.

小题4:This is ________ key.

小题5:Frank ________ OK.

小题6:Eric  and Dave________ good friends.

小题7:What _______these?

小题8:How ________ your father?

小题9:I ________ a boy.

小题10:You ________ good.