口腔前庭内，位于中线上的解剖标志为()
A．切牙乳突
B．舌系带
C．上颊系带
D．下颊系带
E．唇系带
参考答案：E
That was the first time I _____ there and I was impressed by the friendly people very much. [ ]
A. go
B. was going
C. had gone
D. have gone
各级公安消防部队必须建立严格的战备值班制度，保证不间断值班。（）
