表达倍数时，两倍用twice/double, 三倍以上用基数词+times,常见的表达方式如下：
1. 倍数+as…as型
例如：We have produced four times as many computers aswe did last year.我们生产的计算机是去年的四倍多。
2. 倍数+the size of 型
例如：China is almostfive times the size of Mexico in area.在面积上，中国几乎是墨西哥的五倍大。
3. 倍数+what从句
例如：The length of the road is twice what it was three years ago.这条路是三年前的两倍长。
4. 倍数+比较级+than
例如：I am twice older than you. 我的年龄是你年龄的两倍。
5. 比较级+ than…+ by+倍数
例如：The line islonger than that one by twice.这根绳子比那根长两倍。
