滤线栅表面上1cm内的铅条数称为（）

A.栅比

B.栅密度

C.铅容积

D.栅焦距

E.滤线栅因数

The teacher always reminds us, “On no condition_____ you are a Chinese.”

A．should you forget

B．should forget you

C．you should forget

D．forget you should