轧辊的供水目的是什么？
参考答案：冷却和润滑，防止断辊。
More than a dozen students in that school _______ abroad to study medicine last year.
A．sent
B．were sent
C．had sent
D．had been sent
联通用户（含后付费、准预付费、预付费）使用六合卡拨什么号可充值缴费？
