Question

Is it acceptable to change the tense within a paragraph or section from simple present to present perfect or from active to passive . I am critiquing a thesis and the tenses used within paragraphs vary . How should I direct this student

Answer 1

Changing tenses as you described is acceptable (present to present perfect). However, direct the author to maintain the same voice throughout the entire document (either active or passive). Unless the thesis is a highly scientific document, active voice should be used.