病原体自宿主体内排出，并停留在外环境中，然后侵入到新的宿主体内，这是（）
A.传播途径
B.传染过程
C.流行过程
D.传染链
E.传播机制
参考答案：E
The two words have the same pronunciation, but they are different ______ spelling and meaning.
A．in
B．from
C．with
D．about
All of the following are functions of CRM system except（）
A.automation procurement
B.automation sales
C.automation marketing
D.automation customer service
