说明文阅读——电路

火车走(zou)(zou)的(de)(de)路(lu)(lu)(lu)叫(jiao)铁路(lu)(lu)(lu)，汽(qi)车走(zou)(zou)的(de)(de)路(lu)(lu)(lu)叫(jiao)公路(lu)(lu)(lu)。同(tong)样(yang)，输送(song)电(dian)(dian)(dian)流线路(lu)(lu)(lu)叫(jiao)电(dian)(dian)(dian)路(lu)(lu)(lu)。电(dian)(dian)(dian)路(lu)(lu)(lu)通(tong)常由四(si)个部分(fen)组成，即电(dian)(dian)(dian)源、导(dao)线、电(dian)(dian)(dian)器和开(kai)关(guan)。例如手电(dian)(dian)(dian)筒电(dian)(dian)(dian)路(lu)(lu)(lu)，电(dian)(dian)(dian)流从干电(dian)(dian)(dian)池(chi)的(de)(de)正(zheng)极出(chu)发，经过电(dian)(dian)(dian)线、小电(dian)(dian)(dian)珠、电(dian)(dian)(dian)键(jian)，从干电(dian)(dian)(dian)池(chi)的(de)(de)负(fu)极，流回到(dao)电(dian)(dian)(dian)池(chi)里去。

室内照明电路的(de)电源是供(gong)电系统(tong)供(gong)给的(de)。有(you)两根导线，一(yi)根是火线，另一(yi)根是地(di)线。安装都有(you)一(yi)定的(de)规格，开关(guan)要与火线连接。

在同一(yi)电(dian)(dian)(dian)(dian)路(lu)(lu)(lu)中(zhong)常有好(hao)几种电(dian)(dian)(dian)(dian)器(qi)(qi)，连(lian)接(jie)的(de)(de)(de)方法(fa)一(yi)般有串联(lian)(lian)和并(bing)(bing)联(lian)(lian)。串联(lian)(lian)就(jiu)是(shi)把所有的(de)(de)(de)电(dian)(dian)(dian)(dian)器(qi)(qi)按次序依(yi)次接(jie)入电(dian)(dian)(dian)(dian)路(lu)(lu)(lu)中(zhong)。用(yong)(yong)串联(lian)(lian)方法(fa)安装(zhuang)(zhuang)的(de)(de)(de)电(dian)(dian)(dian)(dian)器(qi)(qi)，切断(duan)一(yi)个电(dian)(dian)(dian)(dian)器(qi)(qi)，其它电(dian)(dian)(dian)(dian)器(qi)(qi)也同时(shi)跟着一(yi)起(qi)停(ting)止(zhi)使(shi)用(yong)(yong)。并(bing)(bing)联(lian)(lian)就(jiu)是(shi)把所有的(de)(de)(de)电(dian)(dian)(dian)(dian)器(qi)(qi)的(de)(de)(de)两(liang)端分别连(lian)接(jie)在一(yi)起(qi)，再接(jie)入电(dian)(dian)(dian)(dian)路(lu)(lu)(lu)中(zhong)。用(yong)(yong)并(bing)(bing)联(lian)(lian)方法(fa)安装(zhuang)(zhuang)的(de)(de)(de)电(dian)(dian)(dian)(dian)器(qi)(qi)，切断(duan)一(yi)个支(zhi)路(lu)(lu)(lu)的(de)(de)(de)开关，这个支(zhi)路(lu)(lu)(lu)上的(de)(de)(de)电(dian)(dian)(dian)(dian)器(qi)(qi)停(ting)止(zhi)使(shi)用(yong)(yong)，但不(bu)妨(fang)碍另一(yi)个支(zhi)路(lu)(lu)(lu)的(de)(de)(de)电(dian)(dian)(dian)(dian)器(qi)(qi)正常使(shi)用(yong)(yong)。我们室内(nei)用(yong)(yong)的(de)(de)(de)电(dian)(dian)(dian)(dian)路(lu)(lu)(lu)一(yi)般都是(shi)并(bing)(bing)联(lian)(lian)连(lian)接(jie)。

1.第一(yi)段运用了(le)哪些说明方法？各举一(yi)例(li)。（20分）

答：

2.概括第二段(duan)的(de)大意。

答：

3.用(yong)横(heng)线标出第三段(duan)的中(zhong)心句。

4.第三段用(yong)了哪些说明(ming)方法？各(ge)举一例。

答：

5.用本文的说明对象给这篇文章命一个(ge)标题。