题目

在如图所示的皮带传动装置中，轮A和轮B同轴，A、B、C分别是三个轮边缘上的质点，且rA=rC=2rB.则三个质点的向心加速度之比aA：aB：aC等于：( )   A．4：2：1         B．2；1 : 2C．1：2：4         D．4：1：4   答案：A解析:略 The basketball coach, as well as his team, ______interviewed shortly after the match for their outstanding performance. [     ]A. wereB. wasC. isD. are