数词+times as……as,和数词+times +形容词比较级+than的用法分别是什么?

　　1）倍数表示法
a.主语+谓语+倍数（或分数）+ as + adj.+ as
I have three times as many as you.　我有你三倍那么多.
b.主语+谓语+倍数（分数）+ the size (amount,length…) of…
The earth is 49 times the size of the moon.　地球是月球的49倍.
c.主语+谓语+倍数（分数）+ 形容词（副词）比较级+ than…
The grain output is 8 percent higher this year than that of last year.
今年比去年粮食产量增加8%.

This room is three times as big as that one.这间房的大小是那间房的3倍.
This room is three times bigger than that one. 这间房比那间房大三倍.(也就是这间房的大小是那间房的4倍.)