倍数的表示
1. 表示"几倍大小(长短;数量)"，由"倍数+ the size(length, amount...)"结构组成。如：
The earth is forth-nine times the size of the moon.
2. 表示"……比……大几倍"，由"倍数+形容词(副词)比较级+ than +被比较部分"结构组成。如：
This box is three times bigger than that one.
3. 表示"……是……倍"，由"倍数+ as +形容词+ as +被比较部分"结构组成。如：
Our factory is twice as big as theirs.
