卫氏并殖吸虫的致病虫期是（）
A.虫卵
B.毛蚴
C.尾蚴
D.童虫
E.成虫
参考答案：D, E
To learn English well, we should find opportunities to hear English _____ as much as we can.
A．speak
B．speaking
C．spoken
D．to speak
