婴幼儿易患呼吸系统感染的原因之一是呼吸道黏膜缺乏（）
A.黏液腺
B.纤毛
C.鼻毛
D.IgG
E.SIgA
参考答案：E
---Please sit down and have a break. You have been working for three hours.
---No, thank you. _____.
A．I am not a little tired
B．I am not in the least tired
C．You go ahead please
D．I’ll stop and rest together with you
信托的功能包括（）。
A.财产管理功能
B.融通资金功能
C.社会投资功能
D.社会公益服务功能
E.信用中介功能
