阅读下面短文,用文中括号内所给动词的适当形式填空快啊急用
阅读下面短文,用文中括号内所给动词的适当形式填空.
Forestshelptokeepwaterfromrunningaway,sodrought（干旱）doesn'toftenhappen．Chinesepeoplehavebuilta"GreatWall"oftrees,millionsoftreesacrossthenorthernpartofthecountry．
TheGreatGreenWall1________（be）7,000kilometreslong,anditwillstopthewindfrom2________（blow）theearthaway．It3________already________（save）alotofland．
WangFengisaworkeratYulininShanxiProvince．He4________（work）ontheGreatGreenWallwithmanyotherpeople．We5________（visit）himathisworkplaceandwhenwesawhimhe6________（work）amongthetrees．Hetoldussomethingabouthiswork"Wemust7________（plant）manythousandsoftreeseveryyear,"hesaid"Youseeallthosesmalltreesoverthereonthathill?Thatwassandfiveyearsago．Nowit'sayoungforest!Inafewyears'time,we8________（cover）thosemountainswithtrees,too!"Hepointedtothehighmountainsfaraway．
Wasitdifficult9________（work）ontheGreatGreenWall?
Yes,It'shardwork．butit'sveryimportant．Theonlyproblemiswehaveto10________（grow）ourownfood．ButthankstotheGreatGreenWall,thelandproducesmorecrops．Sothemoretreesthereare,thebetterharvestwehave．"