The first thing    she did was go up to her trainer and thank the trainer  all the help the trainer had given her during the training.

A．which, for

B．that, because

C．that, for

D．what, for

流量计主要有哪两种（）。

A、压差式和测速式

B、压差式和速度式

C、容积式和测速式

D、容积式和涡轮式