题目内容：
根据下面内容，回答题 CanyouimaginehowyouwouldfeelifyoufelldangerouslyillandcouldnotreachorCalladoctor．?
Millionsofpeople（41）theworldareinthisunfortunate（42）,livingindistantplaceswheretherearenorailways,noproperroadsandnotelephones．Thousandsoflivesarelosteveryyearwhichcouldhavebeensavedifmedicalattention（43）intime．
Buttodayhelpcouldbebroughtquicklyandeasilytomanyofthesepeopleifonlyfulladvantagewastakenoftheaeroplane．（44）countryhasprovedthisbetterthanAustralia．TheAustralians（45）greateruseoftheaeroplanethanany（46）peopleintheworld．Innoothercountry（47）thetotalnumberofmilesflownbytheaveragepersonsohigh．Infact,ithasbeen（48）thatAustraliansjumpintoplane（49）peopleinothercountriesjumpintotrainsandbuses．Itisnotsurprising,therefore,thatAustraliashouldhavebeenthefirstcountry（50）aFlyingDoctorService．
第（41）题选 A．on
B．through
C．allover
D．within
参考答案：
答案解析：