"〜 left" という表現は、残りの数や量を明確にしないと使えない。
- I have 300 dollars left.
- I only have two days of vacation time left.
- There isn't very much cake left.
"rest" もしくは "rest of 〜" という表現は、残りの数や量を明確にすることなく使える。
- I was the only American, the rest of the teachers were Canadians.
- I can't eat the rest of this cake.
- Everybody took what they wanted, so we can throw the rest away.