十五英语fifteen。
例句：
1、公司在最兴隆时期每隔十五分钟就开出一列火车。
In its heyday, the company ran trains every fifteen minutes.
2、你家里的电线应该每十到十五年更新一次。
The wiring in your house should be renewed every ten to fifteen years.
3、现在是三点四十五分，我将在四点十五分和你碰面。
It's quarter of four now ─ I'll meet you at quarter after.
4、那时候，大多数人上学只上到十五岁。
In those days most people left school when they were only fifteen years old.
5、三个五等于十五。
Three fives are fifteen.