Sure! Here are the answers for Exercises 3 and 4 in your English homework:

### Exercise 3:
1. I’d like to go to the party, but I’m too busy.
2. It was sunny, so Lan took an umbrella.
3. Anna is an amazing dancer, and her parents are proud of her.
4. You can vote online for your favourite singer, or you can send text messages.
5. Lisa went shopping yesterday, but she didn’t buy anything.
6. John’s parents own a restaurant, and sometimes he helps in the kitchen at weekends.
7. Go inside, or you will catch a cold.
8. Rita is a good drummer, so she will probably be invited to join the band.

### Exercise 4:
1. He likes tea, but he will take a cup of coffee.
2. I bought some books and a school bag.
3. You must accept my offer; otherwise, you will regret it.
4. I will come back right away; don't go anywhere until then.
5. Although Sue studied hard, she has failed the exam.
6. Lewis drove skillfully, yet he could not win the race.
7. The air in the city is highly polluted, so we don’t like to live there.
8. When Christmas season comes, many people decorate their house.

If you need further clarification or help, feel free to ask!