试分析下列说法中何项不正确，并简述理由。

A．砌体的抗压强度设计值以龄期为28d的毛截面面积计算
B．石材的强度等级以边长为150mm的立方体试块抗压强度表示
C．一般情况下，提高砖的强度等级比提高砂浆的强度等级对增大砌体抗压强度的效果好
D．在长期荷载作用下，砌体的强度还要有所降低

—Mike, the office is in a mess; it's your turn to clean it up.

—________ I did it yesterday and the day before yesterday.

A．Don't count on me!

B．Back in a moment!

C．Don't fall for it!

D．Get off my back!