10 Question Based Keyords

Very intesting article mentions 10 types of question based keywords:

1. What’s a good [benchmark/metric] for [process/industry]?
2. How to [increase/improve] [benchmark/metric]?
3. How to find X?
4. How to learn X for free?
5. What are the best [tools/products in a category]?
6. How much does X cost?
7. What’s the best time to do X?
8. How to write X?
9. How to improve X skills?
10.What’s the difference between X and Y? (or X vs. Y)