车床（）箱体中的齿轮，常用溅油润滑。
A．挂轮
B．轴承
C．密封
D．变速
参考答案：C
—Could I use your car tomorrow morning?
—Sure. I ______ a report at home.
A．will be writing
B．will have written
C．have written
D．have been writing
何谓“热因热用”？
