Here are the best answers for each of the questions in the document:

### IV. Choose the best answer a, b, c or d to complete the sentence.

1. **c. for** – "Air pollution has many effects **on** the environment and living organisms."
2. **b. in** – "The villagers are reinforcing their houses to prepare **for** the hurricane."
3. **a. tsunami** – "The **tsunami** flooded the entire port city, and many people became homeless."
4. **b. picking up** – "The volunteers spent the whole day **picking up** litter along the river."
5. **c. Since** – "Since plastic takes so long to break down, it pollutes the land and water."
6. **c. until** – "Tourists love buying traditional handicrafts **until** they visit Vietnam."
7. **b. How long** – "How long do earthquakes usually last? **Less than one minute.**"
8. **c. bargain** – "The open-air market offers many home-grown products, and buyers can **bargain**."
9. **a. destructive** – "The 2010 Haiti earthquake was the most **destructive** natural disaster in the history of this country."
10. **c. Glad to hear** – "‘A hurricane is heading toward our home town.’ ‘**Glad to hear.**’"

### V. Choose the underlined word or phrase, A, B, C or D that needs correcting.

1. **C** – "lead" should be "leads."
2. **D** – "shopped" should be "were shopping."
3. **C** – "fixed" should be "fixed, so you can never bargain for more discounts."
4. **D** – "than" should be "than that of."
5. **A** – "cutting down" is correct but "we're" may be clearer as "will."
6. **A** – "reach" should be "get to" or similar for clarity.
7. **A** – "shows" should be "show."

Make sure to double-check the context to ensure these selections are appropriate!