trillion 万亿靠前个逗号前的数字读成thousand, 1,000 = one thousand第二个逗号前的数字读成million, 1,000,000 = one million第三逗号前的数字读成billion, 1,000,000,000 = one billion第四个逗号前的数字读成trillion, 1,000,000,000,000 = one trillion。