Analysis of test questions: First of all, this question should clarify the important ways for middle school students to participate in democratic decision-making, and exclude the petition system, which is the way for citizens to carry out democratic supervision; From the perspective of middle school students, that is, citizens, to participate in democratic decision-making, you can reflect your opinions and suggestions through deputies to the National People's Congress, and you can also put forward your own suggestions by writing letters, making phone calls and leaving messages on websites. , so ① ② is correct; 3 does not match the meaning of the question. Select one for this theme.