两篇

　　Plantsneedlighttogrow.Infactaplantcannotgrowintheabsenceoflight.Plantsmajorlyactastheproducersintheeconomytherefore,theyproducefoodnotonlyfortheirownusebutalsofortheuseofmen.Lightisverynecessaryfortheplantsbecauseplantstakeenergyfromthesunlightandusethatenergyinmakingfood.Foodisintheformofglucoseanditispreparedbyplantsbyusingcarbondioxideandwaterinthepresenceofsunlight.Thereactionisasfollows:

　　Carbondioxide+Water+Lightenergy------>Glucose+Oxygen

　　Therefore,lightisveryimportantfortheplantsformakingglucoseandtogrow.

　　Alllivingthingsneedlightandheatfromthesuntolive.Plantsneedlightandheattogrow.Theyusethelightfromthesuntomakefood.Wecannotmakeourownfood,butplantscan.Allthefoodweeatcomesfromplantsinafoodchainwhichstartswiththesun.Forexample,animalsneedsunlight,too.Justlikeus,theircomesfromafoodchainwhichbeginswiththesunandtheplants.

　　所有生物都要依靠太阳的光和热而生存.植物需要光和热才能生长,它们接受阳光制造食物.我们无法自行制造食物,但植物可以.我们所吃的所有食物都来自食物链中的植物,而其源头则是太阳.动物也需要阳光.就象我们一样,动物也是食物链中的一环,而食物链正是起源于植物和太阳.