滚动阻力等于滚动阻力系数与车轮负荷之（）
A.乘积
B.和
C.差值
D.反比
参考答案：A
Tom has a little money in the bank, support his family.
A．on which to
B．with that to
C．with that to
D．with which to
有关重复时间（TR）的描述正确的是（）
A.是两个180°射频脉冲之间的时间间隔
B.长TR值用于T2加权和质子密度加权
C.短TR值用于T1加权
D.SE序列T1加权TR为800-3000ms
E.SE序列T2加权TR为400-500ms1
