同步器的基本原理是：用摩擦元件产生的（）使待啮合的齿套与齿圈迅速达到同步。
A、轴向推力
B、切向分力
C、惯性力矩
D、摩擦力矩
参考答案：D
—Your bedroom is so dirty. Would you please _______, Peter?
—OK, mum. I'll do it right away. [ ]
A. set it up
B. put it on
C. pick it up
D. clean it up
化学消化
