普通的床里生长着超过6十亿的尘螨.The average bed is home to over 6 billion mites.每年有超过十亿的观众观看比赛.More than one billion spectators are attracted by the game every year.成年人饮酒的相关问题每年要花费英国几十亿的钱.Adult drink - related problems cost the British...