做徒手体操时，单位时间内动作重复的次数是指（）。
A、动作的频率
B、动作的速度
C、动作的节奏
D、动作的幅度
参考答案：A
You should understand the traffic rule by now. You've had it _____ often enough. [ ]
A. explaining
B. to explain
C. explain
D. explained
七大洲中面积最小的洲是[ ]
A、大洋洲
B、亚洲
C、非洲
D、南极洲
