椭圆齿轮流量计中的椭圆齿轮靠流量计进出口的（）推动而旋转。
A、流量变化
B、压力差
C、流速大小
D、宽、窄
参考答案：B
.
Walking alone in the deserted village, John was scared. He thought he ______Tom to go with him.
A．might have asked
B．should ask
C．must have asked
D．should have asked
影响砖砌体灰缝饱满的因数有（）。
A.灰缝厚度
B.砂浆的和易性
C.砌筑方法
D.立皮数杆
E.灰缝横平竖直
