在样本率与总体率比较的假设检验中，率的抽样误差大小表示（）。

A.由于混杂因素而引起的样本率与总体率之间的差别

B.由于重复测量而引起的样本率与总体率之间的差别

C.由于抽样而引起的样本率与总体率之间的差别

D.由于来自不同总体而产生的差别

E.由于研究者经验不足而引起的差别

What is the maximum capacity in cups of a pail that contains only sand and is filled to three fourths of its capacity ？（）
(1)If one cup of sand were added to the pail, it would be filled to seven eighths of its capacity.
(2)If two cups were removed from the pail, it would be filled to one half of its capacity.

A．条件(1)充分，但条件(2)不充分．

B．条件(2)充分，但条件(1)不充分．

C．条件(1)和(2)单独都不充分，但条件(1)和条件(2)联合起来充分．

D．条件(1)充分，条件(2)也充分．

E．条件(1)和条件(2)单独都不充分，条件(1)和条件(2)联合起来也不充分．