#英语四级考试完形填空模拟练习题（44） 搜索结果
Therocketengine,withitssteadyroarlikethatofawaterfallorathunderstorm,isanimpressivesymbolofthenewspaceage.Rocketengineshave1powerfulenoughtoshootastronauts2theearth'sgravitationalpulland3themonthemoon.Wehaveno
