Пояснення:

Present Perfect Continuous з використанням "since" або "for":

1. I have been studying art since 2018.

2. How long have you been wearing your glasses? (for how long - спитання, тому "for" використовується автоматично)

3. Have you been swimming all afternoon? (no time expression, тому використовуємо без "since" або "for")

4. It has been raining for two hours now.

5. We have not been watching the match.

6. My parents have been studying English for five years.

7. How long has Joanna been working in that café?

Відповіді на другий пункт:

2. How many paintings have you sold/been selling?

Правильний варіант: "How many paintings have you sold?" (Present Perfect, без "been selling")

3. We have travelled/been travelling for a couple of weeks now.

Правильний варіант: "We have been travelling for a couple of weeks now." (Present Perfect Continuous)

4. The professor has answered/been answering more than 100 questions about the Louvre.

Правильний варіант: "The professor has answered more than 100 questions about the Louvre." (Present Perfect, без "been answering")

5. John has known/been knowing Cynthia since primary school.

Правильний варіант: "John has known Cynthia since primary school." (Present Perfect, без "been knowing")

6. I've seen/been seeing most of his paintings.

Правильний варіант: "I've seen most of his paintings." (Present Perfect, без "been seeing")

7. How long have you waited/been waiting?

Правильний варіант: "How long have you been waiting?" (Present Perfect Continuous)