一定量气体膨胀做功100J，同时从外界吸热40J，气体内能的增加ΔU是（ ）A．60J B．-60J C．-140J D．140J
已知CuSO4溶液分别与Na2CO3溶液、Na2S溶液的反应情况如下： （1）CuSO4 +Na2CO3 主要：Cu2+ + CO32─ + H2O == Cu（OH）2↓+ CO2↑次要：Cu2+ + CO32─== CuCO3↓（2）CuS
20世纪五六十年代，日本经济持续高速发展的外在原因是 A．美国的扶持 B．允许土地买卖 C．实行“科技立国”政策
已知函数的部分图象如图所示，则f（0）= A． B．—1 C．
HGPRT缺陷症的致病基因在X染色体上，患儿发病时有自残行为。下图是某一家族系谱图。请分析回答。 （1）此病的致病基因为 性基因。理由
One day Mr. Jackson took Paul to his favorite restaurant．It was a French restaurant．The waiter was from France．But he didn’t speak to them in French．“Would you like to see the menu?”he a
An excellent teacher is believed to be one who devotes himself to the children but asks for nothing. A. in turn B. in advance C. in short D. in return
____ I had done it I knew I had made a mistake. A. Hardly B. Directly C. mostly D. Nearly
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B. 
C. 
D. 
