- How do/does/did...?
- What procedures or actions...?
- What problems...?
- What happens when...?
- What is/was the role of... in...?
- What is/was the difference between...?
- What causes/caused...?
- What are/were the effects/results of...?
- How/why did... decide to...?
- Who/what influenced...to...?
- What is/was the relationship between...and...?
- What are the competing sides...?
- How does/did... change...?
(question stems from The Thoughtful Researcher-- Libraries Unlimited)