单选题：QuestionsarebasedonthefollowingpassageOnceuponatimeapoorfarm

Questionsarebasedonthefollowingpassage
Onceuponatimeapoorfarmertakingasackofwheattothemilldidnotknowwhattodowhenitslippedfromhishorseandfell（41）theroad．Thesackwastooheavyforhimto（42）,andhisonlyhopewasthatpresentlysomeonewouldcomeridingbyand（43）ahand．
Itwasnotlongbeforeariderappeared,butthefarmer'sheartsankwhenhe（44）him,foritwasthegreatmanwholivedinacastlenearby．Thefarmerwouldhavedaredtoask（45）farmertohelp,oranypoormanwhomighthavecomealongtheroad,buthecouldnotbega（46）ofsogreataman．However,assoonasthegreatmancameuphegot（47）hishorse,saying"Iseeyou'vehadbadluck,friend．HowgooditisthatI'mherejustatthe（48）time．"Thenhetookoneendofthesack,thefarmertheother,andbetweenthemtheylifteditonthehorse．
"Sir,"askedthefarmer,"howcanIpayyou?"
"Easilyenough,"thegreatman（49）．"Wheneveryouseeanyoneelseintrouble,（50）thesameforhim．"
第（41）题选 A．on
B．in
C．off
D．onto