. She makes _______ effort to learn maths and she has made _______ great progress in it.

A．an ; a

B．/ ; a

C．the ; /

D．an ; /

血吸虫是通过哪种方式感染的

A．喝了有毛蚴的水
B．接触了血吸虫病人
C．吃了血吸虫卵
D．吃了螺狮
E．尾蚴钻入皮肤