Ответ:

2)B

3) C

4) D

5) A

6)E

4.

2) C

3) A

4) B

2) If factories stop pouring chemicals into rivers, they would be less polluted.

3) If  people didn't leave rubbish in parks, they wouldn't be dirty.

4) If people stop using aerosols, it would help the environment.

Объяснение:

Номер 3

2-B

3-C

4-D

5-A

6-E

Номер 4

2 C

3 A

4 B

2.If factories stop pouring chemicals into rivers, they would be less polluted.

3.If people didn't leave rubbish in parks, they wouldn't be dirty.

4.If people stop using aerosols, it would help the environment.