表示“速度快”的倍数，可用形容词fast 或名词speed 表达。

1. twice faster than = twice as fast as：是两倍快；快一倍

2. three times faster than = three times as fast as：是三倍快；快两倍

3. twice the speed of：是两倍快；快一倍。

4. three times the speed of：是三倍快；快两倍

两倍和两次，一般用twice，很少用two times。