Here are the answers to the questions based on the context given:

**I. Choose the correct answer.**

1. Pollutions are harmful **to** human health. (C)
2. **Contaminated** water resulted in the death of many aquatic animals. (B)
3. What would you do if a factory in your neighborhood **dumped** untreated water into the river? (B)
4. Have you ever heard about the **effects** of radioactive pollution? (D)
5. **Thermal** pollution is the increase of temperature caused by human activity. (A)

**II. Choose the letter A, B, C or D to complete each sentence.**

1. Viet Nam is trying **to preserve** traditional Quan Ho singing. (B)
2. The children like planting trees **because** it’s helpful for the environment. (C)
3. Some people have to book tickets in advance **to** attend the exhibition about noise pollution. (C)
4. Tom wants to take part **in** the environmental project. (D)
5. Harry gets a lot of money **because** he works hard. (D)

Feel free to ask if you need any further assistance!