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农作物生长不仅需要阳光、空气和水，还需要多种化学元素。当植物缺乏N元素时，表现为植株生长缓慢、发黄，严重时叶片脱落直至死亡。 （1）下列可作氮肥的化合物是 ，其中含N量最高的是 。 A．硫酸铵 B．磷酸二氢钙 C．硫酸钾 D．尿素 （2）氮肥的制备，首先涉及氨的合成，请填写下列合成氨工艺流程图中的设备名称： A B （3）某化工厂为了综合利用生产过程中的副产品CaSO 4 ，与相邻的合成氨厂联合设计了以下制备（NH 4 ） 2 SO 4 的工艺流程： ①沉淀池中发生的主要反应方程式是 ； ②在上述流程的沉淀池中通入足量氨气的目的是 ，可以循环使用的X是 ； ③从物质的性质和工业生产实际的角度考虑该流程的主要缺陷是 。
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A.
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B.
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attended
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A.
reveals the relationship between sleep problems and age
B.
provides evidence that lack of sleep affects people's health
C.
puts forward the theory that sleep problems are a kind of disease
D.
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carried away
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