传播途径
参考答案：
病原体离开传染源到达另一个易感者的途径称为传播途径。包括：呼吸道传播、消化道传播、接触传播、虫媒传播、血液、体液传播。
"It is no need ________ there now" means the same as "There is no need ________ there now". [ ]
A. going; to go
B. to go; going
C. going; going
D. to go; to go
Word文档默认的扩展名是( )。
A．dot
B．doc
C．txt
D．word
