_____all the representatives still not there ，the meeting was postponed for several hours.
B
with加名词短语，表示原因，本句意思为：“因为所有的代表还没有到场，会议被推迟了好几个小时”。而because(因为)引导的是原因状语从句，其后必须是个从句。by为“到⋯⋯为止”。
Theagriculturalrevolutioninthe19thcenturyinvolvedtwothings：theinventionoflabor-savingmachineryandthedeyelopmentofscientificagriculture.Labor-savingmachinerynaturallyappearedfirstwherelaborwasscarce.“InEurope，”saidThomasJefferson，“theobjectistomakethemostoftheirland，laborbeingabundant：hereitistomakethemostofourlabor，landbeingabundant.”ItwasinAmerica，therefore，thatthegreatadvancesin19thcenturyagriculturalmachineryfirstcame.
Attheopeningofthecentury，withtheexceptionofacrudeplowfarmerscouldhavecarriedpracicallyalloftheexistingagriculturalimplementsontheirbacks;by1860，mostofthemachineryinusetodayhadbeendesignedinanearlyform.Themostimportantoftheearlyinventionswastheironplow.Asearlyas1790CharlesNewboldofNewJerseyhadbeenworkingontheideaofacast-ironplowandspenthisentirefortuneinintrodueinghisinvention.Thefarmers，however，wouldhavenoneofit，claimingthattheironpoisonedthesoilandmadetheweedsgrow.Nevertheless，manypeopledevotedtheirattentiontotheplow，untilin1869JamesOliverofSouthBend，Indiana，turnedoutthefirstchilled-stillplow.?
1.Whatisthemaintopicofthepassage?
a.Theneedforagriculturaladvancestohelpfeedagrowingpopulation.
b.Thedevelopmentofsafermachinesdemandedbythelabormovement.
c.Machinerythatcontributedtotheagriculturalrevolution.
d.NewJerseyasaleaderintheagriculturalrevolution.
2.Theexpression“makethemostof”inLine4isclosestinmeaningtowhichofthefollowing?
a.getthebestyieldfrom
b.raisethepriceof
c.makefulluseof
d.earnalivingon
3.WhichofthefollowingcanbeinferredfromwhatThomasJeffersonsaid?
a.EuropewaschangingmorequicklythanAmerica.
b.EuropehadgreaterneedoffarmmachinerythanAmericadid.
c.Americawasfinallyrnningoutofgoodfarmland.
d.TherewasashortageofworkersonAmericanfarm.
4.Itcanbeinferredthatthewaord“here”inLine4refersto_____.a.Europe
b.America
c.NewJersey
d.Indiana
5.Whatpointistheautormakingbystatingthatfarmerscouldcarrynearlyalltheirtoolsontheirbacks?
a.Farmershadfewtoolsbeforetheagriculturalrevolution
b.Americansweretraditionallyself-reliant.
c.Lifeonthefarmwasextremelydifficult.
d.Newtoolsweredesignedtobeportable.
Itwasnotuntilshehadfinishedallherwork_____.