题干

下列做法符合安全用电常识的是(  )


A:用电器的三角抽头可以插入两孔插座中使用

B:使用测电笔时,金属体笔尖应该接触被测导线,手指按住金属体笔尾,不能碰到金属体笔尖

C:有人触电时应迅速用手把他拉离电源

D:家庭电路中开关接在火线或零线上都可以

上一题 下一题 0.0难度 选择题 更新时间:2015-05-25 10:31:41

答案(点此获取答案解析)

B

同类题3

阅读下面短文,从短文后各题所给的四个选项(A、B、C和D)中,选出可以填入空白处的最佳选项。

    Wi-Fi is a wireless networking technology used across the globe. A 1 misunderstanding is that the term Wi-Fi is short for “wireless fidelity(保真度)”. However, this is not the case. Wi-Fi is 2 a trademarked phrase that uses the 802.11 standard, which was 3 by the Institute of Electrical and Electronics Engineers (IEEE). That is to say, instead of using 4, your computer is connected to the internet or other computers by radio.

    This standard was 5 promoted by the Wi-Fi Alliance, a trade group that pioneered commercialization of the 6. A person or business can use a wireless router( 路由器) or a similar 7 to create a “hotspot” or an area in which proper devices can connect wirelessly to a network or 8 Internet access. This router is usually connected to the Internet by 9 of a modem, often one   10 as a high-speed connection. Any user within about 200 feet of the 11 point can then connect to the Internet, 12 for good transfer rates, distances of 100 feet or less are often suggested. Salespersons also sell signal boosters(放大器)that  13 the range of a wireless network.

    Wi-Fi networks can either be 14 or closed, in which case a 15 is needed. An area blanketed in wireless access through a device is often called a “wireless 16.” Anyone with a device that  17 proper functionality can connect to this network while in the hotspot. Through this connection, a 18 network can be accessed or Internet connectivity can be achieved. This allows people within the hotspot to connect to the Internet via the router and modem, often 19 for employees at a business or as a free 20 at coffee shops and similar locations.