花岗石中的石英在753℃时，体积发生剧烈膨胀，使花岗石爆裂，甚至松散。所以花岗石怕受火烤，施工和生活过程中应引起注意。( )

The students want to know ____ 1,600 words in a month.

A．how can they remember

B．how they can remember

C．when could they remember

D．when they could remember