Answer:
A verb is a word used to describe an action, state, or occurrence, and forming the main part of the predicate of a sentence, such as hear, become, happen.
1. Verb: Cooks, Ending: S
Explanation: Cooking is a action. 
2. Verb: Uses, Ending: IZ
Explanation: Uses is a action. 
3. Verb: buys, Ending: Z
Explanation: Buying something is an action. 
4. Verb: Costs, Ending: S 
Explanation: Because costing something to someone is a action. 
5. Verb: Knows, Ending: Z 
Explanation: knowing something is technically a action. 
6. Verb: watches, Ending: IZ 
Explanation: Watching something is a action. 
7. Verb: Misses, Ending: IZ
Explanation: Missing someone or something is an action. 
8. Verb: Thinks, Ending: S
Explanation: Thinking is an action