1. Words have weight, sound and appearance; it is only by considering these that you can write a sentence that is good to look at and good to listen to. 2. I was busy trying to figure out whether he had told me the truth. 3. His brother's emotion was not easy to discern. 4. His proposition was worth considering. 5. Everyone in this room is competent to express an opinion. 6. The picture is definitely worth buying. 7. You see, a lot of us are prone to forgetting/prone to forget it. 8. The girl was very wise to take their advice. 9. He was busy working on the new play. 10. I was fascinated to watch the two of them together.
1. is
2. yours
3. by
4. or