A．一定做匀速直线运动
B．一定做直线运动
C．可能做曲线运动
D．可能做圆周运动
答案：C
At the foot of the hill you could hear nothing but the of the clear running water .[ ]
A. noise
B. voice
C. sound
D. noisy
—What do you think of Pete?
—He's _________ than his sister. He talks a lot every day. [ ]
A. quiet
B. quieter
C. outgoing
D. more outgoing
