Readingcomprehension.Thesunisthelargestsourceoflight.Weknowthatlifeontheearthdependsontheheatofthesun.Butthelightofthesunisasnecessarytolifeasitsheat.Anotherimportantsourceoflightisproducedby

　　Readingcomprehension.

　　Thesunisthelargestsourceoflight.Weknowthatlifeontheearthdependsontheheatofthesun.But

　　thelightofthesunisasnecessarytolifeasitsheat.Anotherimportantsourceoflightisproducedbyelectric

　　sparksintubeswhichhasspecialgases.Thatisknownasindirectlight.Thelightweseedirectlyfromthe

　　sourceoflightsuchassunisknownasdirectlight.

　　Laser(激光)isanewkindoflightsource.Itpossessesaseriesofremarkablepropertieswhichmakesit

　　abetterlightsourceinanumberofcases.

　　1.Whichistrueinthefollowing?

　　[ ]

　　Ａ:Thelightmadebyelectricsparksintubeswithspecialgasesiscalleddirectlight.

　　Ｂ:Sunlightiscolourless.

　　Ｃ:Indirectlightissentfromthepowerstationandsoon.

　　Ｄ:Humanbeingsaswellasallanimalsdependondirectlight.

　　2.Whichisfalseinthefollowing?

　　[ ]

　　Ａ:Sunlightisakindofdirectlight.

　　Ｂ:Formansunlightisamuchmoreusefullightthananyotherlight.

　　Ｃ:Electriclightismoreremarkablethanlaserinresearch.

　　Ｄ:Actuallymoonlightcomesfromthesun.

　　3.Lifeontheearthcan'tlive____.

　　[ ]

　　Ａ:withsunlight

　　Ｂ:withoutsunlight

　　Ｃ:withmoonlight

　　Ｄ:withoutmoonlight

　　4.Laserasyouknow____.

　　[ ]

　　Ａ:hasnotbeenwidelyused.

　　Ｂ:hasnotbeenresearched

　　Ｃ:isstillunknown

　　Ｄ:islessusefulthananyotherlight

　　5.Theword"source"means____.

　　[ ]

　　Ａ:源

　　Ｂ:系

　　Ｃ:种

　　Ｄ:类