A is smaller than B by 2, a+2=b, …

2. Multiple relationships.

A is twice as much as B. 2b=a，…

3. The relationship of "ratio".

The ratio of a to b is 2. a:b=2(a？ b=2)……

4. Score relationship (percentage relationship)

A is 1/2 of B. b 1/2 = a，…

A is more than b1/2; B 1/2= more, b( 1+ 1/2)=a, ...