1. My brother ... (stay) with us for three weeks, he hasn't left yet. 2. It... (rain) hard since morning, I can't go for a walk.3. How long ... you ... (look) for her? It's strange that you can find her nowhere.4. The sun is shining but the ground is wet because he ... (water) the garden for a long time.5. She looks very tired. What... she ... (do)?6. He is a good player, because he ... (play) chess since he was five.7. We can't see paths in the garden, because it... (snow) heavily during the whole night.8. He ... (write) his summary since the lecture began.9. I... (buy) food here since I came to this town. ​

1. My brother has been staying with us for three weeks; he hasn't left yet.

Explanation: The verb "has been staying" is in the present perfect continuous tense, which is used to talk about an action that started in the past and is still ongoing. In this case, the action of staying started three weeks ago and is still happening.

2. It has been raining hard since morning; I can't go for a walk.

Explanation: The verb "has been raining" is in the present perfect continuous tense, which is used to talk about an action that started in the past and is still ongoing. In this case, the action of raining started in the morning and is still happening.

3. How long have you been looking for her? It's strange that you can't find her anywhere.

Explanation: The verb "have been looking" is in the present perfect continuous tense, which is used to talk about an action that started in the past and is still ongoing. In this case, the action of looking for her started in the past and is still happening.

4. The sun is shining, but the ground is wet because he has been watering the garden for a long time.

Explanation: The verb "has been watering" is in the present perfect continuous tense, which is used to talk about an action that started in the past and is still ongoing. In this case, the action of watering the garden started in the past and is still happening, so the ground is wet.

5. She looks very tired. What has she been doing?

Explanation: The verb "has been doing" is in the present perfect continuous tense, which is used to talk about an action that started in the past and is still ongoing. In this case, the action of doing something has made her tired.

6. He is a good player because he has been playing chess since he was five.

Explanation: The verb "has been playing" is in the present perfect continuous tense, which is used to talk about an action that started in the past and is still ongoing. In this case, the action of playing chess started in the past when he was five and is still happening.

7. We can't see paths in the garden because it has been snowing heavily during the whole night.

Explanation: The verb "has been snowing" is in the present perfect continuous tense, which is used to talk about an action that started in the past and is still ongoing. In this case, the action of snowing started during the night and is still happening.

8. He has been writing his summary since the lecture began.

Explanation: The verb "has been writing" is in the present perfect continuous tense, which is used to talk about an action that started in the past and is still ongoing. In this case, the action of writing his summary started when the lecture began and is still happening.

9. I have been buying food here since I came to this town.

Explanation: The verb "have been buying" is in the present perfect continuous tense, which is used to talk about an action that started in the past and is still ongoing. In this case, the action of buying food started when the person came to the town and is still happening.