以下哪个与膨胀水箱连接的管路要设阀门：（）。
A.膨胀管
B.循环管
C.信号管
D.溢流管
参考答案：C
下列属于生物的是[ ]
A．恐龙骨骼
B．木马
C．小草
D．钟乳石
—Allan looks tired out.
—Sure. He in the gym for two hours.
A．works out
B．had worked out
C．has been working out
D．was working out
