Enabling and Disabling form controls HELP!!

Here is what I need to do using and select box or radio buttons for question #1, a select box for question 2 and 3.

Question 1 has three choices (Yes, Maybe, No). If "Yes" or "Maybe" is selected then question 2 is enabled. If "No" is selected then Question 3 select box is enabled.

Its that simple but I'm having problems writing the query.