by three and a half billion years ago

by three and a half billion years ago three-and-a-half billion about three and a half months ago 英语翻译Three and a half years ago,our organization submitted re three-and-a-half years from three and a half years什么意思 three years and half a year a billion and a half by two thousand twenty,a billion and a half people will live - years ago ,I came to the USA.Two and a half Two and half a 翻译：a billion and half dollars began to skate__ A for three and a half years B three and a