Answer:
Have you ever visited the capital city of your country?
A: Yes, I have just visited the capital city of my country.
Has your brother (or sister) left school?
A: No, my brother (or sister) hasn't left school yet.
Have you climbed the highest mountain in your country?
A: No, I haven't climbed the highest mountain in my country yet.
Have you sent a text to your friend today?
A: Yes, I have already sent a text to my friend today.
Have you answered a question in class today?
A: No, I haven't answered a question in class yet.