4. - These apples aren't ripe enough to eat them

- These apples are too unripe so we cann't eat them

5. - The sutiation is too complicated so I can't explain

- The suitiation isn't simple enough to explain

6. - The wall was too high, so we couldn't climb over.

- The wall wasn't enough low to climb over

7. - This sofa isn't big enough to three people sit on 

- This sofa is too small so three people cann't sit on 

Cấu trúc chung : 

I. Cấu trúc với "enough ...to": đủ ...để làm gì

1. Đối với tính từ:
Cấu trúc: S + be + adj + enough + (for somebody) + to V

2. Đối với trạng từ:
Cấu trúc:  S + V + adv + enough + (for somebody) + to V

3. Đối với danh từ:
Cấu trúc: S + V/tobe + enough + noun + (for somebody) + to V

II. Cấu trúc với "too...to": quá ...đến nỗi không thể

1. Đối với tính từ:
Cấu trúc: S + be + too + adj + (for somebody) + to V

2. Đối với trạng từ:
Cấu trúc: S + V + too + adv + (for somebody) + to V