WLAN业务如何计费的？
参考答案：使用WLAN业务只收取WLAN数据流量费（按时长计费），无功能费和信息费。
将各种氨基酸结合在一起形成肽链的键被称为（）
A.氢键
B.肽键
C.二硫键
D.共价键
E.非共价键
As we are _____ Table Cloth, we should be pleased if you would send us your best quotations.
A．in the market for
B．on the market for
C．entering the market for
D．at the market for
