I.
1. He couldn't meet you because he was busy.
2. She went to bed early because she was sick.
3. We spent the whole day in the garden because the weather was lovely.
4. I can't play volleyball because I am short.
5. We can't swim in this part of the river because the water is highly polluted.
II.
1. She is very old, so she can’t work hard.
2. She is very beautiful, so he likes her.
3. He was careless, so he broke the vase.
4. His life was hard, so he left school.
5. I feel tired, so I went to bed early.
III.
1. occurs -> occurred
2. interestingly -> interesting
3. after
4. role -> part
5. which -> although
6. whom -> who
7. forecast weather -> weather forecast
8. ought bring -> ought to bring
9. so -> because
10. chicken -> chickens
VI.
1. I am writing this letter to complain about the noise from Apartment 3C.
2. I moved into Apartment 2C on November 1st.