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计算题：某浮选矿浆需压力管道输送，已知输送管道临界管径为0.3m，输送矿浆流量为0.1m3/s，求矿浆输送的临界流速。

答案

参考答案：

VL=4Q/（πDL2）==（4×0.1）/（3.14×0.09）=1.42m/s

矿浆输送的临界流速为1.42m/s。

单项选择题 A1型题

外伤性血气胸最简便可靠的诊断依据是（）

A.呼吸困难

B.胸透见有液气面

C.胸穿抽出血液和气体

D.气管移位
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单项选择题

The following data sufficiency problems consist of a question and two statements, labeled (1) and (2), in which certain data are given. You have to decide whether the data given in the statements are sufficient for answering the question. Using the data given in the statements plus your knowledge of mathematics and everyday facts (such as the number of days in July or the meaning of counterclockwise), you must indicate whether.

x=0.57y9. If y denotes the thousandth digit in the decimal representation of x above, what digit is y ？（）
(1) If x were rounded to the nearest tenth, the result would be 0.6.
(2) If x were rounded to the nearest hundredth, the result would be 0.58.

A. Statement (1) ALONE is sufficient, but statement (2) alone is not sufficient.

B. Statement (2) ALONE is sufficient, but statement (1) alone is not sufficient.

C. BOTH statements TOGETHER are sufficient, but NEITHER statement ALONE is sufficient.

D. EACH statement ALONE is sufficient.

E. Statements (1) and (2) TOGETHER are NOT sufficient.
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