I don't work at home, ___ a rule. Which word completes the sentence?

• A. As
• B. In
• C. With
• D. By

Answer: (A)

The main idea is using the fixed expression as a rule, which means generally or usually. When you want to state something as a general habit, you can add this phrase after your main clause with a comma: I don't work at home, as a rule. The other options don’t form a natural idiom to express general habit: in a rule or with a rule aren’t used in this sense, and by a rule means something like “according to a rule,” which doesn’t fit the idea of a general pattern. So the best fit is as.