题目

一个小朋友从滑梯上匀速下滑的过程中，下列说法正确的是:A．动能减小，重力势能减小;    B．动能不变，重力势能减小;C．动能增加，重力势能减小;   D．动能不变，重力势能不变. 答案：B—What did David demand in the meeting just now?—________ a chance to join the Debating Club.A. Being offered B. Having been offeredC. To be offered D. To have been offered