A

B

1.The seas and the rivers are too dirty to swim in

2.There is too much smoke in the air in many cities in the world 

3.No, they can't

4.Yes, it is 

crow 

1.Jackson is from China 

2.He listens to music in his free time 

3.She is a dancer

4.Yes, she does 

5.Tung is from Vietnam

6.He sufts the internet in his free time 

4cm

1.d

2.e

3.b

4.c

5.a