The wheels of the first road vehicles were fashioned from crude stone disks.
A、hand-carvedB
暂无解析
Themegaphone(microphone)makesthevoicesoundlouderbecauseitpointssoundwavesinonedirectionandkeepsthemfromspreadingoutinalldirections.
Thecontrolsofmostmodernairplanescanbeoperatedeithermanuallyorautomatically.
One of the greatest breakthroughs for professional women came in 1973 when the field of banking opened up for them.
DoubleEagleinthefirsttransatlanticballoon,wasgreetedbyavidcrowdsinFrance.
ThefuturesurvivalofthebaldeagleisstillanimportantAmericanecologicalconcern.
