有一个物体以初速度v0沿倾角为θ的足够长的粗糙斜面上滑，到达最高点之后又加速下滑，那么能正确表示该物体的速度v随时间t变化的图线是(
下列物质属于纯净物的是（ ） A.牛奶 B.冰红茶 C.冰水混合物 D.洁净的空气
Prime Minister’s speech is deeply impressed _________ my memory. A. to B. over C. by D. on
I’ll never forget the moment _____I first met Mary and _____ makes me already feel happy. A. that; that B. which; what C. at which; which D. when; what
有炭粉和氧化铜的黑色固体20g，加热后将生成的气体通入足量的石灰水中，气体全被吸收，产生了10g沉淀，求原混合物的组成。
The little girl could look after ________ though she was only five years old. A. she B. her C. hers D. herself
—If I go to see my friends, I'll bring them some flowers. —______． A．So will I B．So I will C．So do I D．So I do
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,－１