阀芯是调节阀的关键部件，形式多种多样，但一般分为两大类，即直行程阀芯和（）。

A、球形阀芯

B、平板刑阀芯

C、角行程阀芯

D、套筒形阀芯

Happily, the victories of our team came from the Asian Games in Guangzhou __________.

A．one by one

B．one after another

C．little by little

D．one another