by two thousand twenty,a billion and a half people will live

by two thousand twenty,a billion and a half people will live a billion and a half by three and a half billion years ago three-and-a-half billion 翻译：a billion and half dollars two and a half one and one-half billion和one and a half billion那一句常用啊 hundred、thousand、million、billion、trillion等词前加a加and 英语翻译Rome's history spans over two and a half thousand years. a hundred twenty thousand two hours and a half How long will you stay here A.two and a half month B.two and