Helen had a dream to walk to the North Pole alone when she was forty.
海伦四十岁的时候有一个梦想：要独自走到北极。
2
Over the past forty years, China planted billions of trees as part of its fight against expanding deserts, mostly in its north.
在过去的四十年，中国种植了数十亿的树木来作为主要遏制北方沙漠延伸的举措之一。
3
On the nineteenth, my forty-seventh birthday, I announced that Bill Daley of Chicago would become the chair of our task force on the North American Free Trade Agreement.