磷以MgNH4PO4·6H2O形式沉淀，经过滤，洗涤后用适量HCl标准溶液溶解，而后以NaOH标准溶液返滴定，选甲基橙为指示剂，此时磷与HCl的物质的量之比是()。
A. 1：3
B. 3：1
C. 1：2
D. 1：1
查看答案
The author indicates in the passage that conflict______.
A. is an inevitable struggle resulting from competition
B. reflects the struggle among social entities
C. is an opposition among individual social animals
D. can be avoided
In the author's opinion, the speaker______.
A. gave a correct judgement of the English level of students
B. had exaggerated the language problems of the students
C. was right in saying that English teachers were not doing their jobs
D. could think and speak intelligently
Which of the following is the best title for the passage？
A. The Life Cycle of Locusts.
B. Migratory Locusts in the United States.
C. Locust Plagues in Nebraska.
D. The Reproductive Capability of the Locust.
某种可比产品成本降低额=可比产品按上年实际平均单位成本计算的本年累计总成本-本年累计实际总成本。（）
A. 正确
B. 错误
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