怎样预防网络可能出现的问题()
A.经常检查线路或接口是否有漏洞
B.设置防火墙
C.解决静电问题,增加接地线
D.以上都对
参考答案:D
26. His younger sister is often made to cry by him, but this time she made him ______.
A.crying
B.cry
C.to cry
D.cries
采用多级压缩制冷循环的原因?