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问题 单项选择题

患者，30岁，月经一直正常，现在是月经干净后第7天，宫颈黏膜涂片检查结果是典型羊齿叶状结晶，表明( )

A．排卵后
B．接近排卵
C．月经期
D．月经前
E．已妊娠

答案

参考答案：B

填空题

写出与前面词语相对的词语。    

黄鹂对（     ）    翠柳对（ ）

西岭对（     ）    千秋对（ ）
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单项选择题

An analyst wants to get, crate a simple random sample of 500 stocks from all 10000 stocks traded on the New York Stock Exchange, the American Stock Exchange, and NASDAQ. Which of the following methods is least likely to generate a random sample（）

A. Listing all the stocks traded on all three exchanges in alphabetical order and selecting every. 20th stock.

B. Writing the name of each stock on a piece of paper, putting them in a hat, and drawing out 500 names, one at a time.

C. Using the 500 stocks in the S＆P 500.
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