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问题 填空题

我国劳动人民在3000年前的商代就制造出了精美的青铜器．青铜是铜锡合金，它具有良好的铸造性、耐磨性和耐腐蚀性．取青铜样品8.1g，经分析知其中含锡0.9g，则此青铜中铜和锡的质量比是______．

答案

由题意可知，此青铜中含铜的质量为：8.1g-0.9g=7.2g，

则此青铜中铜和锡的质量比是：7.2g：0.9g=8：1．

故答案为：8：1．

选择题

—Are you ready______the exam?

—Yes, I am.                 [ ]

A. for facing                  

B. to face                        

C. face
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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.

In the figure above, with B a point on the line AC, what is the measure of ∠XBZ ？（） (Figure not necessarily drawn to scale.)

(1) BX bisects ∠ABY, which is a right angle, and BZ bisects ∠YBC.

(2) ∠ABX=∠XBY=∠YBZ=∠ZBC

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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