如图所示,在O点处放置一个正电荷.在过O点的竖直平面内的A点,自由释放一个带正电

题型:选择题

问题:

如图所示,在O点处放置一个正电荷.在过O点的竖直平面内的A点,自由释放一个带正电的小球,小球的质量为m、电荷量为q.小球落下的轨迹如图中虚线所示,它与以O为圆心、R为半径的圆(图中实线表示)相交于B、C两点,O、C在同一水平线上,∠BOC=30°,A距离OC的竖直高度为h.若小球通过B点的速度为v,则下列说法正确的是

A.小球通过C点的速度大小是

B.小球在B、C两点的电势能不相等

C.小球由A点到C点的过程中电势能一直都在减少

D.小球由A点到C点机械能的损失是

考点:电势
题型:选择题

测定瓦斯的仪器中常用的有瓦斯检查器和()。

A.测氧仪

B.温度计

C.瓦斯检测灯

D.水压计

题型:选择题

There _________ a 100-metre final at midnight. Would you like to join us to watch it?

A.will have

B.will go to be

C.is going to have

D.is going to be

题型:选择题

全髋关节置换术中,为预防髋臼和髓腔内置入骨粘合剂出现的心血管功能紊乱,以下哪些措施是必要的()

A.出现心动过缓时,可分次静脉注射阿托品

B.置入骨粘合剂前必须维持收缩压在90mmHg以上,必要时使用升压药

C.务必及时补充失血,避免低血容量

D.吸入纯氧

E.为预防血压的突然下降,可静脉点滴多巴胺,以维持血压平稳

题型:选择题

These last few painful moments make me wonder if what my friends told me about college was all true. ①Where are all the beautiful girls I’m supposed to be meeting and talking to in every room? Where are the freedom and relaxed atmosphere my friends bragged about? I’m supposed to be enjoying myself instead of suffering! Everybody seems to have forgotten that college is hard work too. My first days in writing class prove② that delight and pleasure often disappear when assignments are due!

文中①段画线部分正确的翻译是()。

A.我假定在每个教室都要遇见并谈话的漂亮女孩在哪里?

B.我在每个教室都能碰上并和她聊聊天的漂亮女孩在哪里?

C.漂亮的女孩上哪儿去了?不是说随便在哪个教室都能碰上,并和她们聊聊天的吗?

题型:选择题

大泵柱塞润滑用的机油泵是()泵。

A、离心

B、柱塞

C、叶片

D、齿轮

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