( )以股票每天上涨和下降的家数为观察对象，通过比较每日累计情况，形成升跌曲线，并与综合指数对比，对大势的未来进行预测。

A．BOS(超买超卖指标)

B．BIAS

C．ADR(涨跌比指标)

D．ADL(腾落指数)

How long do you think ______ the computer company brings out a new product?

A．it will be before

B．will it be until

C．will it be when

D．it will be that