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【简答题】
（10分）把下列参数方程化为普通方程，并说明它们各表示什么曲线： ⑴、 （ 为参数）； ⑵、 （ 为参数）
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皮皮学刷刷变学霸
举一反三
【单选题】如图所示,一个质量为 m 、电荷量为 q 的带电小球从 M 点自由下落。 M 点距场区边界 PQ 高为 h ,边界 PQ 下方有方向竖直向下、电场强度为 E 的匀强电场,同时还有垂直于纸面的匀强磁场。小球从边界上的 a 点进入复合场后,恰能做匀速圆周运动,并从边界上的 b 点穿出。重力加速度为 g ,不计空气阻力,则下列说法中正确的是 ( ) 。
A.
小球带负电荷，匀强磁场方向垂直于纸面向外
B.
小球的电荷量与质量的比值
C.
小球从 a 运动到 b 的过程中，小球和地球系统机械能守恒
D.
小球在 a 、 b 两点的速度相同
【简答题】Unit 2 Passage A Dog talk: Every dog has its day Americans have many expressions using the word “dog.” Nowadays people in the United States love their dogs and treat them well. They take their dogs fo...
【判断题】Nowadays, more young people tend to enjoy American public holidays and festivals. As for Ms. Chen, she can understand this new trend since young Chinese are willing to accept new things, like Christm...
A.
正确
B.
错误
【简答题】Scientists have reached the conclusion _____ the temperature on the earth is getting higher and higher . A.what B. that C.it D. because 2. I’m not _____ to think I can succeed without efforts . A.n...
【简答题】l Dog talk: Every dog has its day Americans have many expressions using the word “dog.” Nowadays people in the United States love their dog and treat them well. They take their dogs for walks, let the...
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