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【单选题】
社会主义基本制度的确立,为当代中国一切发展进步奠定了A.
制度基础
B.
经济基础
C.
社会基础
D.
群众基础
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【多选题】What is the feature of the de novo pathways for purine and pyrimidine biosynthesis?
A.
The de novo pathways for purine and pyrimidine biosynthesis seem to be nearly identical in all living organisms.
B.
Notably, the free bases guanine, adenine, thymine, cytidine, and uracil are not intermediates in these pathways; that is, the bases are not synthesized and then attached to ribose, as might be expected.
C.
The purine ring structure is built up one or a few atoms at a time, attached to ribose throughout the process. The pyrimidine ring is synthesized as orotate, attached to ribose phosphate, and then converted to the common pyrimidine nucleotides required in nucleic acid synthesis.
D.
Although the free bases are not intermediates in the de novo pathways, they are intermediates in some of the salvage pathways.
【单选题】用铁丝、铜丝和CuSO 4 溶液可以构成原电池或电解池，如图所示则下列说法正确的是
A.
构成原电池时Cu极反应为：Cu—2e - ＝Cu 2+
B.
构成电解池时Cu极质量可能减少也可能增加
C.
构成电解池时Fe极质量一定减少
D.
构成的原电池或电解池工作后就可能产生大量气体
【单选题】从理论上分析,关于Fe— CuSO 4 溶液—Cu原电池的叙述正确的是( )
A.
铜极为负极
B.
电子从铜沿导线转移到铁
C.
铁表面析出金属铜
D.
总反应为 Fe + CuSO 4 = FeSO 4 + Cu
【简答题】房屋的日常维护可分为()和()两种类型。
【简答题】Cu(s)｜CuSO4(m)｜CuSO4(m')｜Cu(s)浓差电池，m较小的一端为正极。
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