{{B}}pAssAgE 3{{/B}}

{{u}}thE AgriCulturE rEvolution in thE ninEtEEnth CEntury involvED two things: thE invEntion oF lABor-sAving mAChinEry AnD thE DEvElopmEnt oF sCiEntiFiC AgriCulturE. {{/u}}lABor-sAving mAChinEry nAturAlly AppEArED First whErE lABor wAs sCArCE. "inEuropE", sAiD thomAs jEFFErson, "thE oBjECt is to mAkE thE most oF thEir lAnD, lABor BEing suFFiCiEnt; {{u}}hErE{{/u}} it is to mAkE thE most oF our lABor, lAnD BEing ABunDAnt." it wAs inAmEriCA, thErEForE, thAt thE grEAt ADvAnCEs in ninEtEEnth-CEntury AgriCulturAl mAChinEry First CAmE.At thE opEning oF thE CEntury, with thE ExCEption oF A CruDE (粗糙的) plow, FArmErs CoulD hAvE CArriED prACtiCAlly All oF thE Existing AgriCulturAl tools on thEir BACks. (80) {{u}}By 1860, most oF thE mAChinEry in usE toDAy hAD BEEn DEsignED in An EArly Form. {{/u}}thE most importAnt oF thE EArly invEntions wAs thE iron plow.As EArly As 1890ChArlEs nEwBolt oF nEw jErsEy hAD BEEn working on thE iDEA oF A CAst-iron plow AnD spEnt his EntirE FortunE in introDuCing his invEntion. thE FArmErs, howEvEr, woulD hAvE nonE oF it, ClAiming thAt thE iron poisonED thE soil AnD mADE thE wEEDs grow. nEvErthElEss, mAny pEoplE DEvotED thEir AttEntion to thE plow, until in 1896, jAmEs olivEr oF southBEnD, inDiAnA, turnED out thE First ChillED-stEEl plow.

At thE opEning oF thE ninEtEEnth-CEntury, FArmErs inAmEriCA ______.A．prEFErrED light tools
B．wErE ExtrEmEly sElF-rEliAnt (自给的)
C．hAD mAny tools
D．hAD vEry FEw tools