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【单选题】
CuI是一种不溶于水的白色固体，它可以由反应：2Cu 2+ +4I - =2CuI↓+I 2 而得到。现以石墨为阴极，以Cu为阳极电解KI溶液，通电前向电解液中加入少量酚酞和淀粉溶液。电解开始不久，阴极区溶液呈红色，而阳极区溶液呈蓝色，同时有白色沉淀生成。下列说法中正确的是A.
对阳极区溶液呈蓝色的正确解释是：2I - -2e - =I 2 ，碘遇淀粉变蓝
B.
对阳极区溶液呈蓝色的正确解释是：Cu-2e - =Cu 2+ ，Cu 2+ 显蓝色
C.
阴极区溶液呈红色的原因是：2H + +2e - =H 2 ↑，使阴极附近OH - 浓度增大，溶液显碱性，从而使酚酞变红
D.
阴极上的电极反应式为：Cu 2+ +2e-=Cu
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leave
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have left
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leaving
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had left
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【单选题】They _____ us willingly but that they happened to be short of hands, too.
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would help
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would have helped
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【简答题】A wise man was walking from one town to another with a few of his followers, and they happened to pass a lake. So they stopped there to 1 for a while, and the wise man said to one of his followers, “I...
【单选题】They______ us willingly but that they happened to be short of hands, too.
A.
would help
B.
would have helped
C.
were going to help
D.
must have helped
【单选题】They happened to__________ for Tianjin when we got there.A.leaveB.have left###SX
A.
They happened to__________ for Tianjin when we got there. A.leave
B.
have left
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leaving
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had left
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