No one can________great achievements unless he concentrates on what he is doing，even though a talent. A．attain B．attract C．apply
如图为两种物质间发生化学反应的微观示意图（一种小球代表一种原子）．下列说法中正确的是（ ） A．图示中共有三种单质分子 B．图示产物为混合
如图所示，A、B为咬合转动的两个齿轮，它们的半径分别为和，且则A、B两轮边缘上两点的角速度之比为= ；线速度之比= 。
由于美元持续贬值、通货膨胀率上升、全求信贷紧缩，国际投资者增持黄金，推动黄金价格上涨。2008年1月11日，金价突破每盎司900美元，黄金之所有受
The day I became a mom was not the day my daughter was born, but seven years later. Up until that day, I had been too busy trying to survive my abusive(辱骂的) marriage. I had spent all my energ
First impressions are the most lasting. After all, you never get __ second chance to make __ first impression. A. a; the B. the; the C. a; a
小明想拍一张雨后晴空的照片，小华建议他加一块滤色镜，小明应选择:A．红滤色镜; B．黄滤色镜; C．蓝滤色镜; D．绿滤色镜.
（12分）已知 （1）解关于的不等式 （2）若不等式的解集为求实数的值 .
