以太网的核心技术是( )。
A．随机争用型介质访问方法
B．令牌总线方法
C．令牌环方法
D．载波侦听方法
参考答案：A
常用硬质合金的牌号有（）。
A、16Mn
B、YT30
C、35
D、T8A
—________?
—She is very friendly and lovely. [ ]
A. What does your teacher look like
B. What is your teacher like
C. Where is your teacher
D. How does your teacher like
