有读者问： twice是否能用在比较级之前？
用twice表两倍时，只可用twice as...as..., 不可用twice more... than..., 如：
(1)He is twice as old as his son. （不可说twice older than...）
(2)There are twice as many houses in this area as there used to be. （不可说twice more houses...than...）
如用two times，则其后既可接as...as..., 亦可接more than...
