----- Why do you think Liu Xiang is one of the best sportsman?

----- ______, he is the world record holder in men’s 110m hurdles, which is considered to be a big progress for Chinese athletes.

A．For the first time

B．Believe it or not

C．To give an example

D．To tell the truth

砂石泵反循环钻进起动前引水是由（）完成的

A、离心水泵

B、3PNL泥浆泵

C、砂石泵