Specific duties are levied ______ some physical unit such as dollars per bushel, per kilo, or per metre and ad valorem duties are calculated as a percent of the value of the goods.

A．on the basis of

B．with the basis of

C．on the base of

D．with the base of

下列哪—项是促胰液素的主要生理作用

A．胰腺分泌大量水分和碳酸氢盐

B．胰腺分泌大量消化酶

C．胃液分泌增加

D．胃蠕动增强

E．胆汁分泌减少