倍数表达
「是……的几倍」的三种句型，高考常考。
倍数 + as … as；倍数 + 比较级 + than；倍数 + the size / length of
要点
- 倍数 + as + 原级 + as：This room is twice as large as that one.
- 倍数 + 比较级 + than：This room is three times larger than that one.
- 倍数 + the + 名词（size / height / length / width）+ of：The new bridge is four times the length of the old one.
- 常见倍数词：half（一半），once（一倍），twice（两倍），three times（三倍）；三倍及以上一般用 times。
- 三种句型意思可以互换：twice as large as = twice larger than（口语中）= twice the size of，考试认准句型结构即可。
- 中英对"倍"的算法差一层：中文「比…多一倍」＝英文 twice as … as（是两倍），中文「增加到三倍」才是 three times … —— 换算时先定"是几倍"。
- increase by + 百分数（增加了…）与 increase to + 数字（增加到…）意思不同，看 by / to 判落点。
- 主语换成 size / length / height 这类名词时，只能走「倍数 + the + 名词 + of」那一条：The new bridge is four times the length of the old one.
例句
Our new school is three times as big as the old one.
我们的新校园是老校园的三倍大。
This line is twice longer than that line.
这条线比那条线长一倍。
The height of the tower is twice the height of the building.
这座塔的高度是那栋楼的两倍。
He runs twice as fast as his brother.
他跑得比他哥哥快一倍。
The price of the ticket has risen by thirty per cent.
票价涨了百分之三十。
This river is four times the length of that one.
这条河是那条河的四倍长。
易错提示
- 倍数必须放在比较结构前面：three times bigger than（不是 bigger three times than）。
- 「一半」用 half as … as：This box is half as heavy as that one.
- 「一半」用 half as … as（This box is half as heavy as that one），别把 half 塞到比较级前面。
- 判这类题只看两件事：倍数有没有放在最前，than 前面是比较级还是原级 —— 两处搭对就不算错。