商务领航定制网关控制QQ、MSN或者BT、e-Male等应用应该使用()功能。
A.防火墙
B.访问控制
C.入侵检测
D.防病毒
参考答案:B
I work very hard because I don't want to . [ ]
A.let my parents down
B.let down them
C.let my parents to be disappointed
D.let my parents go.
接收机适用的输入电平范围是指使BER或FER保持在规定的容限内时具有规定调制信号的RF输入信号电平的范围。()