1. This traffic jam is really bad isn’t it ? ✓

2. We'll waste a lot of water by taking baths, won’t we ? ✓

3. Sara hasn't completed the survey,  has she ? ✓

4. They didn't use to work at the recycling centre,didn’t they?✓  

5. You recycle all your plastic bags,  do you? ✓

6. There were lots of people at the event, weren’t there?​ ✓

Good luckツ