华支睾吸虫病的主要传染源包括()
A．鼠
B．病猫
C．病犬
D．患者
E．猪
参考答案：A, B, C, D, E
如果正n边形的每一个内角都等于144°，那么n=______．
Not until he left his home _______to know how important the family was for him. [ ]
A. did he begin
B. had he begun
C. he began
D. he had begun
