They were very (worry) ... when they heard that there had been an accident

1. As it gets closer, the shops get more and more (crowd)......
2. They were very (worry).......when they heard that there had been an accident
3. Mai usually gets good marks in Physics because she thinks it is an (interested).......subject to study
4. You must be very (care)........when you ride your bike in crowded streets
5. Nam has been studying very hard. I believe he'll pass the exam (easy)........
6. A good driver always thinks about the (safe)........of his passengers