1. The secretary signed the letter (in/on/at) behalf of her boss.
2. You must study this paragraph (by/in/at) detail.
3. Why can't you look at the problem (in/to/from) my point of
view.
4. We need sales people who can work (on/at/by) their own initiative.
5. Harry managed to sell his house (on/in/at) a very high price.​