bài 4 

1. we can find fewer skycrapers in rural area than in the city

2. jane can finish fewer task than i can

3. i have been to more countries in the world than marria

4. my mother bought fewer litres of milk than she did last week

5. my watch is less expensive than hers

6. this year they will plant more trees than they did last year

bài 5.

1. as=> than ( so sánh hơn )   2. patient=> patients ( N/ người bệnh ) 

4. fewer=> less (confidence ko đếm được )   5. mouse=> mouses   

6. less=> fewer ( fish số nhiều vẫn là fish )   7. problem=> problems