当总体方差未知，置信度为1-α时，总体均值的置信区间为()。
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The word proponents in the passage is closest in meaning to
A. formulas.
B. supporters.
C. objects.
D. designers.
The word they in the passage refers to
A. academies.
B. conventions.
C. members.
D. ideals.
Why does the man go to see his professor？
A. He is worried about the professor's class.
B. He wants to bring up the grade in her class.
C. He would like some advice about his classes.
D. He needs to get the woman's signature.
The word solidifying in the passage is closest in meaning to
A. confirming.
B. invalidating.
C. determining.
D. clarifying.
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