D twice as many
这个涉及倍数表达法
1. “A+倍数+形容词或副词的比较级+than+B”，表示“A比B大（长、高、宽等）多少倍”。如：
This rope is twice longer than that one.这根绳子比那根绳子长两倍（是那根绳子三倍长）。
This hall is five times bigger than our classroom.这个大厅比我们的教室大五倍(是我们教室的六倍大)。
The car runs twice faster than that truck.这辆小车的速度比那辆卡车快两倍（是那辆卡车的三倍快）。
2.“A+倍数+as+形容词或副词的原级+as+B”，表示“A正好是B的多少倍”。如：
Asia is four times as large as Europe.亚洲的面积是欧洲的四倍。
This big stone is three times as heavy as that one.这块大石头的重量是那块的三倍。
The plane flew ten times as high as the kite.那架飞机的飞行高度是那只风筝的十倍。
3. “A+倍数+the size/height/length/width, etc+of+B”，表示“A正好是B的多少倍”。如：
This street is four times the length of that one.这条街是那条街的四倍长。
This hill is four times the height of that small one.这座山的高度是那座小山的四倍。
除掌握倍数表达的三个常规句型外，我们更要注意的是其常规句型的变形及其特殊规律。
一.常规句型的变形
1. “ ... times+more+名词（可数或不可数）+than+被比对象”。如：
There are five times more books in our library than in yours.我们图书馆里的书比你们图书馆多五倍多。
We have produced twice more grain this year than we did last year.我们今年生产的粮食是去年的两倍多。
2. “ ... times as many/much+名词+as+被比对象”。如：
There is four times as much water in this pot as in that one.这个壶里装的水是那个壶里的四倍。
There are six times as many students as we expected.学生数量是我们预期的六倍。
3.“ ... times+over+被比对象”。如：
The grain output in that village is twice over that of 2002.那个村的粮食产量是2002年的两倍多。
4. “ ... times+that+of+被比对象 ”。如：
In this workshop, the output of July was 4.5 times that of January.这个车间7月份的产量是1月份的4.5倍。
5. “...times+compared with+被比对象”。如：
The number of the students in our school has increased 4 times compared with 1980.我们学校的学生人数比1980年增加了四倍。
6. “...times+what+从句”。如：
The production is now three times what it was ten years ago.现在的产量比十年前增加了三倍。
二.倍数/百分数（percent）+compared with/up on +被比对象。如：
Our factory ' s output of TV sets in the first six months of this year was 10% up compared with last year.今年头六个月我们厂电视机的产量与去年相比增加了10%。
The industrial output of last year in our factory was 35% up on that of 2001.我们厂去年的工业产量比2001年增加了35%。
三.用double表示倍数
1. double用作形容词，表示“两倍的”。如：
The production is now double what it was ten years ago.现在的产量是十年前的两倍。
2. double用作动词，表示“是……的两倍。如：
The output has been doubled in the past six years.在过去六年中产量已经翻了一番。
This brought a steady rise in the grain yield. In 2002 it nearly doubled that of 1980.这使粮食产量不断增长，到2002年产量已经比1980年将近翻了两番。
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