如果想表达一个数字比另一个大多少，有很多种表达方式，如果表示倍数的话可以使用times 和as...：
The man is THREE TIMES AS OLD AS his grandson.
我们可以说3 Times As Old As, 但不能写 3 Times Older Than. 同样可以写3 Years Older Than, 但是不能写3 Years As Old As.当然使用times 的时候不一定要用as 或than ：
Right: The cost of a ticket is $12, SIX TIMES the cost ten years ago.
Right: The concert was attended by 300 people, TWICE the previous attendance.
而如果想表示两个数字的加或减则要用more than 或less than ：
Right: I am TEN years OLDER THAN you.
Wrong: I am TEN years AS OLD AS you.
More 和less 可以当作名词代词，也可以用作形容词副词等：
Right: I own MORE THAN I should. (more = noun or pronoun)
Right: I own MORE SHIRTS THAN I should. (more = adjective)
Right: I sleep MORE THAN I should. (more = adverb)
而其他表示数比较的词如high 和low 只能做形容词：
Right: My bills are LOWER than they were last year.
Wrong: I spend LOWER than I did last year.
Right: I spend LESS than I did last year.