雅思倍数用法
在雅思写作中，表达倍数的常见方式有以下几种：
主语+谓语+倍数+as+形容词/副词原级+as
例如：The grain output is three times as high as last year.
主语+谓语+倍数+the size（amount, length...） of
例如：The earth is 49 times the size of the moon.
主语+谓语+倍数+形容词（副词）比较级+than
例如：The grain output is 8% higher this year than last year.
by+倍数
例如：The number of people attended the concert increased by twofold.
倍数+as big as 或 倍数+as many as
例如：The number of students in class A is twice as big as that of class B.