Well, thank you.

Thank you for taking the time to help me (us) fill out this questionnaire

Next, you should write down the research purpose of your questionnaire.

For example, this questionnaire is mainly to understand your ~ ~ ~ (if the purpose of the study is not convenient to disclose, it can be vague, such as understanding your psychological state.

Answer questions, for example, please read the topic clearly and mark what on it. This should be concise and clear.

Thanks again. (generally, thank you at the beginning and the end. )

I wrote it myself, not standard.