Several large musical companies are reported________with major online music providers in China at present about charging individual users for music downloads.

A．discussing

B．to discuss

C．having discussed

D．to be discussing

主要用于查找重大非法事项，有极高的可信赖程度的抽样方法是（）。

A.固定样本抽样

B.变动样本抽样

C.随机抽样

D.发现抽样