Sam is a little boy, and he is only seven years old. One day he goes to the cinema(电影院). It is the first time for him to do that. He buys a ticket and then goes in. But after two or three min
微波炉是一种家用的食品加热炉，它利用了A．电流的热效应 B．光波的能量 C．红外线的热作用 D．微波的能量
根据欧姆定律，下列说法正确的是 A．从R=U/I可知，导体的电阻跟加在导体两端的电压成正比，跟导体中的电流成反比 B．从R=U/I可知，对于某一确定的导
清末民初山西有一首歌谣：破戏台，烂秀才，小足板子洋烟袋；火车站，德律风（指电话），大足板子毕业生。这反映出当地
Robert is said _____ abroad, but Idon’t know what country he studied in. A. to havestudied B. to study C. to be studying D. tohave been studying
The fact puzzled Jack much ________ he has been unable to pass the driving test up to now. A. why B. because C. how D. that
科学史上每一次重大发现都极大的推进了科学的发展，俄国科学家门捷列夫对化学的突出贡献在于（ ） A．提出了元素周期律 B．开发了合成氨的生产
如图，在矩形ABCD中，1.请完成如下操作：①作的平分线AE交BC边于点E；②以AC边上一点Ｏ为圆心，过A、E两点作圆Ｏ（尺规作图，不写作法，保留作图痕
