Question 14: Dr Lam, __ research focuses on rainforests, is particularly concerned about the impact of deforestation on plant and animal life. A. whose B. who C. that D. which Question 15: Most of us are America, __ some are immigrants from other countries like Viet Nam, India, and Mexico. A. so B.or C. despite D. but Question 16: The exchange student who we invited __ our club comes from the Philippines, so his English is so good. A. to join B. join C. joining D. joined

Here are the answers and explanations for the questions:<br /><br />**Question 14:**<br /><br />* **Correct Answer:** A. whose<br />* **Explanation:** The sentence needs a possessive pronoun to connect the research to Dr. Lam. "Whose" is the correct choice because it shows that the research belongs to Dr. Lam.<br /><br />**Question 15:**<br /><br />* **Correct Answer:** D. but<br />* **Explanation:** The sentence expresses a contrast between the majority being American and some being immigrants. "But" is the conjunction that best conveys this contrast.<br /><br />**Question 16:**<br /><br />* **Correct Answer:** A. to join<br />* **Explanation:** The sentence needs a prepositional phrase to show the purpose of the invitation. "To join" is the correct choice because it indicates the action of joining the club. <br />