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【多选题】
下列关于咖啡因的理化性质叙述不正确的是A.
和强酸、如盐酸能生成稳定的盐
B.
有一定的碱性但碱性极弱
C.
分子中的基本为黄嘌呤生物碱，所以用紫脲酸铵反应鉴别
D.
分子中具有酰脲结构故遇酸不稳定
E.
咖啡因的饱和水溶液遇碘化汞钾时也会产生沉淀
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【单选题】Music is the result of thought in the form. of attitude. There is no one way of thinking, since men's values are as scattered and dissimilar as individual men themselves. If black music can be seen as...
A.
Due to environmental influences, the music of black and white artists must be very different.
B.
Due to its result of thought, Mack artists' music can be learned by white musicians.
C.
Because jazz is created on inspiration, it is difficult for musicians to copy each other.
D.
Because music has social significance, its influence on black white relations should not be underestimated.
【单选题】Music is the result of thought in the form. of attitude. There is no one way of thinking, since men's values are as scattered and dissimilar as individual men themselves. If black music can be seen as...
A.
Due to the environmental influences, the music of black and white artists must be very different.
B.
Due to its result of thought, black artists' music can be learned by white musicians.
C.
Because jazz is created on inspiration, it is difficult for musicians to copy each other.
D.
Because music has social significance, its influence on black white relations should not be underestimated.
【单选题】Since there seems no way to get out of the present depressions, the future of the company looks pretty .
A.
optimistic
B.
dismal
C.
intolerable
D.
implicit
【单选题】Is there any possible ______ explanation for his bad health since he seems to have no obvious disease?
A.
psychiatric
B.
psychological
C.
surgical
D.
physical
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