雌激素中生物学活性最强的形式为()
A.雌酮
B.17β-雌二醇
C.雌三醇
D.雌四醇
E.结合型雌激素
参考答案:B
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
在能力计划中,工艺线路设计、时间定额以及物资消耗定额是关键的三个要素。其中时间定额是指正确确定物资需要量,编制物资供应计划的重要依据。