图示某半开的阀门，阀门前后测压管水头差△h=1m水柱，管径不变，管中平均流速v=2m/s，则该阀门的局部阻力系数ζ为()。
A. 4.9
B. 6.1
C. 3.4
D. 4.2
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甲公司20×8年12月购入一项固定资产，当日交付使用，原价为630万元，预计使用年限为10年，预计净残值为300万元，采用直线法计提折旧。2×12年末，甲公司对该项固定资产的减值测试表明，其可收回金额为3 300万元，预计使用年限、净残值及折旧方法均不变。2×13年度该项固定资产应计提的折旧额为()万元。
A. 630
B. 600
C. 550
D. 500
The barber advised(建议)John ______.
A. to have his hair cut short
B. to cut off most of his hair
C. to be cut off his long hair
A．The US should catch up to European environmental standards.B．American exporters must
A. The US should catch up to European environmental standards.
B. American exporters must adapt to new regulations in Europe.
C. The US should be more sensitive to environmental issues.
D. The U's new regulations are a burden.
What CANNOT be inferred from the first paragraph？
A. Scientific experiments in the past three hundred years have produced many valuable items.
B. For three hundred years there have been people holding a hostile attitude toward science.
C. Modern civilization depends on science so man supports scientific progress unanimously.
D. Some people think three hundred years is not long enough to set hack for critical appraisal of scientific method.
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