Unclear Subject Practice

Are the dependent clause introductions to these sentences written correctly?  Is the subject clear?  If not, edit the sentence.

1. During math class, Klause forget to turn in his homework.
2. While eating lunch, the picnic area got really windy and cold.
3. Though sick, the project turned out to be the best one in the room.
4. Since early times, weather has been a predictor of mood.
5. When early, the office allows them to play on the playground.
6. Though young, the kids deeply respected what their grandparents had lived through.
7. Though old, the babies made them feel young again.
8. Whenever possible, cats like to lie in the sun.
9. Understanding nothing, the French-English dictionary was never far from Marnie's side.
10. Hopeful, the corpse had some unusual identifying marks.