依据交通原则建立起来的中心地体系，上级中心地可以支配下级中心地( )的商服活动。
A．全部
B．1/2
C．1/3
D．1/6
参考答案：B
As a ( ) salesman, he can write and speak in foreign language, as well as sing and dance.
A. flexibleB. versatileC. productiveD. sophisticated
鼻旁窦囊肿中最为常见的是（）
A.上颌窦含牙囊肿
B.上颌窦牙根囊肿
C.鼻旁窦黏液囊肿
D.鼻旁窦黏膜囊肿
E.滤泡囊肿
