若方程 (a2-4)x2+(2-3a)x+(a+1)y+3a=0为二元一次方程,则a的值为( )。
It is reported that up to now, mountain slides have cut off more than ten villages from the outside
world, ______more than one hundred people alive and ______ many houses. [ ]
A. buried; destroyed
B. burying; destroying
C. to bury; to destroy
D. being buried; being destroyed
划分Vlan不是实现Qos常用的技术。