have been (Answer 1)
I have been thirsty for four hours.
Present Perfect Tense
The Present Perfect Tense forms with has/have + Past Participle.
We use the Present Perfect Tense when an action started in the past and it continues in the present.
We use the Present Perfect Tense to express a repeated action in a period of time between the past and the present.
We use the Present Perfect Tense when an action was completed in the very recent past.
We also use the Present Perfect Tense when we talk about life experience.
1. My dad has played the guitar since he was a child. (Affirmative)
2. He has written five books since he left school. (Affirmative)
3. I have just taken the medicine. (Affirmative)
4. Have you been to South Korea in the last year? (Interrogative)
5. Have you ever met Aaron Kwok? (Interrogative)
6. Have you read the book yet? (Interrogative)