有关气源交输活门,下列哪种说法是错误的?()
A.发动机地面起动时开。
B.APU为空调供气时开。
C.空中大翼防冰时开。
D.平时自动关闭,空中打开。
参考答案:D
Tom's parents were not happy about his grade in the examination, _____. [ ]
A. he himself was neither
B. neither was he himself
C. he himself was either
D. either was he himself
关于IM通信协议的描述中,正确的是()
A.SIP基于SIMPLE
B.QQ基于SIP通信
C.XMPP基于JABBER
D.SIP工作于网络层