You can pool question items so that students will get different questions from this one bag.
In order to pool questions together, click on question in an assignment you'd like to create a pool with. Scroll to the bottom and click the green + next to 'Question Pooling' to add a question.
Click Add, and search for questions (or enter in a question id) you'd like to pool, add questions as you normally would.
Be sure to click 'display questions at random' in order for one of these to be randomly displayed to students.
When you have pooled questions together you will see it displayed as several lines:
