For this question, can I get an answer that different then others? those seem wrong, thanks!

Consider scanning literals for representing carbohydrates in chemistry. Such literals consist of one or more parts, each consisting of C, H, or O, optionally followed by a decimal integer greater than 1 (it can greater than 9). You may use D0 to mean decimal digits 0-9, D1 to mean 1-9, and D2 to mean 29. (This is a computer science question, not a chemistry question. In particular, this specification allows bogus chemical formulas such as H₄₂.)

1. Give a regular expression for these carbohydrate literals. You may use the iteration operators * and + and ?.

([CHO]([2-9]|[1-9][0-9]+)?)( ) this is what i have can you check this?

1. Give a DFA that recognizes exactly these literals (no edges). Dont forget to mark the start state and all accepting states.

Make sure that you dont accept the empty string!