Question

I'm looking for a example for 1 to 2 ratio sentence

Answer 1

For every cup of flour you need two cups of sugar...
1:2
1 cup flour to 2 cups sugar.

Answer 2

To add to Ms Pi's example,
ratios can have more than 2 terms.

e.g. to make concrete, you should mix
water : cement : gravel (sand) = 1 : 2 : 3

in words: use 1 part water with 2 parts cement and 3 parts sand.