置信区间的大小受()的影响。
A、总体平均值
B、平均值
C、置信度
D、真值
参考答案:C
Some people will never learn that you can't get something for ______. [ ]
A. something
B. anything
C. everything
D. nothing
厚煤层分层开采的采煤方法有()
A、倾斜分层走向长壁上行垮落法;
B、倾斜分层走向长壁下行垮落法;
C、水平分层走向长壁采煤法;
D、斜切分层走向长壁采煤法;
E、倾斜分层倾斜长壁上行充填法。