属特殊黏膜
A．舌腹、口底黏膜 B．硬腭黏膜 C．口底、牙龈黏膜 D．舌背黏膜 E．龈、颊黏膜
参考答案：D
除了差错检测外，面向字符的数据链路层协议还必须解决哪些特殊的问题
Some political analysts feel that the power of the northeastern United States is on the wane.
A．old-fashioned
B．dwindling
C．stabilizing
D．forgotten
