It is hard for the Greek government to get over the present difficulties_________ gets more financial support from the European Union.

A．if

B．unless

C．because

D．since

以下不是PrPc和PrPcs的区别的是（）

A、PrPc蛋白酶水解完全

B、PrPcs蛋白酶局部水解

C、PrPc蛋白酶水解产物氨基酸

D、PrPcs蛋白酶水解产物是氨基酸