You are not old enough to drive a car.

2. I like coffee better than tea.

 I prefer coffee to tea.

3. That shirt is too dirty to wear.

 That shirt isn't clean enough to wear

4. His car isn't as fast as yours. 

  His car is slower than yours.

5. My tea is too hot to drink.

   My tea isn't cool/cold enough to drink. 

6. I like  eating traditional food better than fast food.

  I'd rather eat traditional food than fast food.

7. Travelling by bus is cheaper than travelling by train.

  It is more expensive to travel by train then by bus.

8. The Headmaster was stricter than the other teachers.

   The other teachers were less strict than the Headmaster.

9. This box is too heavy for me to carry.

   This box isn't light enough for me to carry.

10.I can understand German more easily than I can understand French.

    I can't understand French as easily as I can understand German.