IV. Fill in each blank with a suitable preposition. (5 pts)
1. Hoa's new skirt was white ___________ yellow flowers ___________ it.   
2. Some young people are concerned ___________ the environment and work on neighborhood clean-up campaigns.      
3. He was trying his T-shirt ___________ when his friend came in.             
4. He finished his work ___________ less than 10 minutes before he came to visit his friends.      
5. After finishing the task, please compare your answers ___________ your friends'.           
6. Enjoying your food you eat is also the key ___________ a healthy lifestyle.             
7. I have just received a letter ___________ my aunt in which she wrote a lot ___________ her and her family  
8. Eating too much candy and staying up late too often are very bad ___________ your health.