往复泵启动时，泵体内（）。
A、须充满液体
B、须排气
C、不能充满液体
D、不须充液
参考答案：D
—What would you like?
—I am hungry. I would like________.[ ]
A. eating something
B. eating anything
C. anything to eat
D. something to eat
用电信息采集系统采用GPRS通信方式与无线电台、电力载波比较（）
A.抗干扰性强
B.成本非常高
C.系统容量小
