
智能变电站交换机VLAN配置的必要性为()。
A.减轻交换机和装置的负载
B.采用VLAN技术,有效隔离网络流量
C.安全隔离,限制每个端口只收所需报文,避免无关信号干扰
D.控制数据流向,提高网络可靠性、实时性


A.减轻交换机和装置的负载
B.采用VLAN技术,有效隔离网络流量
C.安全隔离,限制每个端口只收所需报文,避免无关信号干扰
D.控制数据流向,提高网络可靠性、实时性
完形填空
阅读下列短文,从每小题所给的A、B、C、D四个选项中选出一个最佳选项。
Lisa is serious about the chores in her house, She gives her children thiings that they ___16___ do according to their ages. She started by asking John, the ___17___ of her two sons, to help with the dishes, It is now an easy chore ___18___ the 15-year-old. His 13-year-old brother, Dave, now ___19___ John too. They take turns(轮流)was hing the ___20___ each week. The boys also clean their study tables, make their beds and ___21___ food from the market on Sunday mornings. Besides(除了)these, the boys also know how to cook easy meals ____22____ their parents are not at home.
The family of ____23___ live in a big house but they do all the housework themselves. Lisa says, "When I was young, my father wanted us to do things on our own and learn how to ___24___ ourselves. Now I'm doing it to my kids." John says, "Doing chores is ___25___. You can learn important life skills and responsibility(责任)."
16.A.must B.can C.may D.will
17.A.elder B.taller C.younger D.shorter
18.A.with B.as C.for D.by
19.A.likes B.finds C.hates D.helps
20.A.hands B.dishes C.fruit D.clothes
21.A.borrow B.cook C.buy D.sell
22.A.when B.how C.what D.why
23.A.two B.three C.four D.five
24.A.work on B.live in C.look at D.take care of
25.A.difficult B.good C.bad D.boring
垄断是自由竞争的对立物,因而垄断消灭了竞争。