BGP通过以下哪种报文协商MP-BGP能力（）。
A.OPEN
B.Update
C.Notification
D.keepalive
参考答案：A
牛顿的关于三大定律的巨著所采用的书写语言是（）
A、英语
B、希腊语
C、法语
D、拉丁语
When he lived in that remote place, radio was the only means he had to keep ______ of current events in the country.
A．account
B．trace
C．record
D．track
