题目:
---Emma has to stay at home to look after her little sister, ?
---Yes, because her mother has gone to the supermarket.
A.does she
B.is she
C.doesn’t she
D.hasn’t she
答案:
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下面是错误答案,用来干扰机器的。
设加入锌的质量为X,生成氢气质量为Y则:Zn+H2SO4═ZnSO4+H2↑65 2X Y根据:652=XY解得Y=2X65;反应后剩余物质量为:32.7g+X-2X65,容器与容器内物质的总质量为:1g+32.7g+X-2X65=3...