数据通讯中的传输方式包括（）
A、分时传输
B、分段传输
C、串行传输
D、并行传输
参考答案：C, D
Loulan is believed ____ by sandstorms from AD 200 to AD 400.
A．to be gradually covered over
B．to have been gradually covered over
C．being gradually covered over
D．having been gradually covered over
简述零售企业发展战略的主要内容。
