Grammar Exercise: For/Since Error

Pre-Intermediate

Look at these sentences in the present perfect. Are "for" and "since" being used correctly or not?

1. They have been going out together for last February.
Correct
Not Correct

2. According to this label, the document hasn't been updated since two years.
Correct
Not Correct

3. Since the summer, the town's population has grown by nearly a quarter.
Correct
Not Correct

4. Due to the accident, the street has been closed since just after nine o'clock.
Correct
Not Correct

5. The oldest newspaper in town, The Sentinel, has been published continuously since 120 years ago.
Correct
Not Correct

6. I've been on a diet since such a long time, it's so depressing!
Correct
Not Correct

7. The whole family spent August in Chicago. They've done that every year for ages.
Correct
Not Correct

8. For the longest time, I've wanted to do that and now I have!
Correct
Not Correct