题目

如图所示，光滑绝缘水平桌面上有A、B两个带电小球（可以看成点电荷），A球带电量为+2q，B球带电量为﹣q，由静止开始释放后A球加速度大小为B球的两倍。下列说法正确的是（） A . A球受到的静电力是B球受到静电力的2倍 B . 靠近过程中A球的动能总是等于B球的动能 C . A球受到的静电力与B球受到的静电力是一对平衡力 D . 现把A球与带电量为+4q的C球接触后放回原位置，再静止释放A、 B两球，A球加速度大小仍为B球的2倍 1. In memory of the 90th anniversary of the founding of the communist party of China , our school held a c__________of singing a few days ago 2.If it is c _______ to you, please pay a visit to me when your are in town.3.We must be a _____ of the skillful methods used in ads to try and sell us things. 4.In defeat, they found something more p ______ than victory---they found friendship, hounour and respect. . 5. Due to the terrible flood, most of the farmlands in our southern have been d_________ recently. 6.Although the power was cut off yesterday, the hospital still f________ (运作)normally. 7.At what age are children able to ____________(区分) between right and wrong ? 8.We should be fully aware of the ___________(重要性) of television in shaping our ideas. 9.After the chemical works exploded last week, much __________(有毒的 ) gas was given off. 10.A technique used f _____（频繁）by many players is to stare at the people they are playing against to make them feel uncomfortable.