制动器常见故障？
参考答案：
1）制动力矩逐渐减小。2）制动器突然失灵。3）制动轮温度过高，制动带冒烟。4）制动器打不开。5）易于脱开调好的位置。
______ is often the case with children, Amy was better by the time the doctor arrived.
A．It
B．That
C．What
D．As
急性肾盂肾炎的疗程通常为
A．1周
B．2周
C．3周
D．5周
E．1个月
