用逗点区分:
第一个逗号是“千”;
第二个是“百万”;
第三个就是“十亿”.
所以,为便于读清楚,我用分割线分开来给你:
1) twelve thousand (12 加上 ,)
2)5 million / two hundred and thirty thousand;
3) sixty-seven million / three hundred and thrity five thousand/ seven hundred
4) twelve billion/ five hundred and sixty million /five hundred thousand