2018版高中英语（人教版）选修9同步教师用书：Unit 4 Period Ⅰ 单元预习课.doc

《2018版高中英语（人教版）选修9同步教师用书：Unit 4 Period Ⅰ 单元预习课.doc》由会员上传分享，免费在线阅读，更多相关内容在教育资源-天天文库。

1、Unit4　ExploringplantsPeriodⅠ　单元预习课植物是我们生活中必不可少的一个部分，那么你知道植物的重要性吗？Plantsformthebasicfoodstapleforalllifeforms.Theyarethemajorsourceoffoodandoxygenonearth，sincenoanimalcansupplythesenecessarycomponentswithoutplants.Therearemanydifferenttypesofcashcropsthatproducemoneyforfarmers.Oliveoilcomesfro

2、molives，cornoilcomesfromcorn，andpeanutoilcomesfrompeanuts.Typicalagriculturalproductslikecorn，wheat，rye，andriceareallconsideredcashcrops.Coffeeplantsproducebeansthatareusedtomakecoffee；cocaplantsgiveuschocolate；vanillaplantsgrowlongthinbeansthatareusedtoproducevanillaflavoring.Plantsarealsous

3、edinagriculturetohelpreducewindspeed.Plantingtreesinarowpreventsthewindfromblowingawaythevaluabletopsoil.Intheforest，treesactasshelterformanyorganisms.Plantsarealsoimportantfortheoverallecologyofanarea.Rootshelptostabilizesoilandpreventthesoilerosionbywaterrunoff.Plantsarealsoimportantinourat

4、mospherebecausetheyusecarbondioxideandgiveoffoxygenwhiletheyundergophotosynthesis.Plantsarealsousedintheurbansettingtoreducenoise，produceshade，andtobeautifyanarea.Treesaddvaluetohomesandcommunities.Plantsareessentialtothebalanceofnatureandinpeople'slives.Greenplants，i.e.，thosepossessingchloro

5、phyll(叶绿素)，producetheirownfoodandgiveoffoxygenintheprocesscalledphotosynthesis(光合作用)，inwhichwaterandcarbondioxidearecombinedbytheenergyoflight.Plantsaretheultimatesourceoffoodandmetabolicenergyfornearlyallanimals，whichcannotproducetheirownfood.Besidesfoods，plantproductsvitaltohumansincludewoo

6、dandwoodproducts，fibers，drugs，oils，latex，pigments，andresins.Coalandpetroleum(石油)arefossilsubstancesofplantorigin.Thusplantsprovidepeoplenotonlysustenancebutshelter，clothing，medicines，fuels，andtherawmaterialsfromwhichinnumerableotherproductsaremade.1．Whatisthepurposeofthesecondparagraph?______

7、__________________________________________________________2．Whyareplantsimportanttoouratmosphere?________________________________________________________________【答案】　1.Givesomeexamplesabouttheuseofplants.2．Becausetheyusecarbondioxideandgiveof