阅读理解。

Themodernageisanageofelectricity.Peoplearesousedtoelectriclightsradiotelevisionsand

telephonesthatitishardtoimaginewhatlifewouldbelikewithoutthem.Whenthereisapowerfailure

peoplegropeaboutinflickeringcandlelightcarshesitateinthestreetsbecausetherearenotrafficlights

toguidethemandfoodspoilsinsilentrefrigerators.

Yetpeoplebegantounderstandhowelectricityworksonlyalittlemorethantwocenturiesago.Nature

hasapparentlybeenexperimentinginthisfieldformillionofyears.Scientistsarediscoveringmoreandmore

thatthelivingworldmayholdmanyinterestingsecretsofelectricitythatcouldbenefithumanity.

Alllivingcellssendouttinypulsesofelectricity.Astheheartbeatsitsendsoutpulsesofrecord;they

formanelectrocardiogramwhichadoctorcanstudytodeterminehowwelltheheartisworking.Thebrain

toosendsourbrainwavesofelectricitywhichcanberecordedinanelectroencephalogram.Theelectric

currentsgeneratedbymostlivingcellsareextremelysmalloftensosmallthatsensitiveinstrumentsareneeded

torecordthem.Butinsomeanimalscertainmusclecellshavebecomesospecializedaselectricalgenerators

thattheydonotworkasmusclecellsatall.Whenlargenumbersofthesecellsarelinkedtogethertheeffects

canbeastonishing.

Theelectriceelisanamazingstoragebattery.Itcansendajoltofasmuchaseighthundredvoltsof

electricitythroughthewaterinwhichitlives.(Anelectrichousecurrentisonlyonehundredandtwentyvolts

buttwohundredandtwentyvoltsinChina.)Asmanyasfour-fifthsofallthecellsintheelectriceel'sbodyare

specializedforgeneratingelectricityandthestrengthoftheshockitcandelivercorrespondsroughlytolength

ofitsbody.

1.Electricitywasinvented______.

[ ]

A.whenmanhadnocandles

B.about200yearsago

C.tobeoperatingcomputers

D.byThomseEdison

2.Thefollowingthingscansendoutpulsesofelectricityexcept______.

[ ]

A.electriceelsan