Test content validity refers to the degree to which the test questions represent the range of content tested. According to the above definitions, which of the following is behaviors to check the validity of the content? . ['In order to evaluate the teaching quality of a teacher, a college conducted a questionnaire survey among teachers in the students. The content of the survey is extensive, including teaching methods, teaching attitudes, teacher dressing, teaching languages, etc.', 'In order to check whether the difficulty of the test content during the period is appropriate, Mr. Wang surveyed 20 students and found that students generally reflected that the test was difficult.', 'In order to check whether the highly competitive college entrance examination is effective, the relevant units conducted a follow-up survey on candidates who entered the university to see if they can adapt to university studies.', 'The national unified qualification exam for project managers has added some new test points this year. The state has organized special personnel to evaluate the newly added test content to see if it has actually passed the test content in actual work.']