Ответ:

1. Nicole's parents weren't as strict with her brother as with her.

2. If it hadn't rained we would have gone to the beach yesterday

3. It's very kind of you, but you needn't pick me up ( or there's no need to pick me up) at my house. I can walk to restaurant

4. He shouldn't have left his laptop all night. Now it needs charging.

5. If I had known, I wouldn't have told anyone.

6. She hurt her head when she fell of her scooter. She should have worn a helmet