Fill the sentences with more, less or fewer

Bài 2: Fill the sentences with more, less or fewer.

1.February has ______ days than January.

2.Overpopulation is causing ______ problems than we can imagine.

3.Big cities suffer ______ pollution than the countryside.

4.A teacher needs ______ calories than a farmer.

5.A healthy child requires _____ care than a sick one.