人工井底是指（）。
A、套管内水泥塞高度
B、套管内阻流环深度
C、套管内水泥塞深度
D、套管外水泥塞深度
参考答案：C
— How did I do on ________ test?
— Well, actually you didn't do very well. I wonder if you had had ________ good review of your lessons. [ ]
A. a; a
B. the; the
C. a; the
D. the; a
一个物体自静止开始做加速度逐渐变小的加速直线运动，经过时间t，末速度为vt，则这段时间内的位移 [ ]
A、x < vtt /2
B、x = vtt /2
C、x > vtt /2
D、无法确定
