There are two ways to preview an assessment: from the Submission side and the Evaluation side. These options are so that you can see the tests exactly as your students will and so that you can fine tune your assessment.
From the Assessment Canvas, hover over the Preview button on the menu.
The Submissions Preview page shows what a student will see when taking the assessment. To preview each question, click on it's name.
TheEvaluation Overview page offers a view of all of the evaluations, regardless of their status. When you click on a user name you will be taken to "their" submission. Remember these are only examples so you can see what your students see. There is also a Status column (evaluation completed or not) and a Points Allocated column. Students can review and change their evaluations any time during the evaluation period that you set as the instructor when you created or edited an assessment.