With the new technique ______, the factory produced ______ family cars in 2009 as the year before.[ ]

A. to introduce; three times many as

B. introduced; three times as many

C. introducing; three times as many

D. being introduced; three times many as

锅炉的水质如果不进行处理，其较严重的危害是（）。

A．形成水垢、发生汽水共腾等事故

B．烟气爆炸、烟道尾部二次燃烧

C．发生满水或缺水事故