It was many years ____ American women were given the rights to vote.

A．when

B．since

C．before

D．as

确定计算监理费的基数是采用( )的关键。

A．按时计算法

B．固定价格计算法

C．工资加一定比例的其他费用计算法

D．按建设工程投资的百分比计算法