. With two months _______,we'll have to say good-bye for our school life will be ending.

A．going

B．gone

C．goes

D．to go

水质硬度过高，配料方法又不当，如添加苯甲酸钠过多时，则与柠檬酸作用生成（）的小亮片状的苯甲酸沉淀。