I. 1)Because he was busy, he couldn't meet you .

2)Because she was sick, she went to bed early. 

3)Because the weather was lovely, we spent the whole day in the garden. 

4)Because I am not tall, i can't play basketball. 

5)Because the water is highly polluted, we can't swim in the part of the river. 

II. 

1)Because she is very old , she can't work hard .

2)He likes her because of her beauty. 

3)He broke the vase because of being careless. 

4)He left school because of his hard life. 

5)I went to bed early Because of feeling tired. 

III. 

1)polluted

2)carefully 

3)carelessly 

4)disappointed 

5)pollution 

I.

1.Because he was busy,he couldn't meet you.

2.Because she was sick,she went to bed early. 

3.Because the weather was lovely,we spent the whole day in the garden. 

4.Because I am not tall,I can't play basketball. 

5.Because the water is highly polluted,we can't swim in the part of the river. 

II. 

1.Because she is very old,she can't work hard .

2.He likes her because of her beauty. 

3.He broke the vase because of being careless. 

4.He left school because of his hard life. 

5.I went to bed early Because of feeling tired. 

III. 

1.polluted

2.carefully 

3.carelessly 

4.disappointed 

5.pollution