Tom is a _______ person. He thinks no one can be successful without ________.

A．hard-working, hard work

B．hard-working, work hard

C．working-hard, hard work

D．working-hard, work hard

压送式比例混合系统是依靠（）方式。

A.水力压送

B.专用泡沫液泵压送

C.气压压送

D.电力压送