What is the general clue at the beginning of the questionnaire?

1) salutation and greetings. For example, "hello, sir and madam".

2) Investigators explain the identities of the organizers and individuals of the survey.

3) Briefly explain the content, purpose and filling method of the survey.

4) Explain the meaning or importance of the answer.

5) explain the required time.

6) Ensure that the answer has no negative influence on the respondent and keep it confidential.

7) Express sincere thanks or explain that a small gift will be given.