3. The best sightings of the northern lights often __ between 11pm and midingli. D. host A. locate B. occur C. measure 4. Tourists couldn't __ admiring the magnificent view of the Victoria Falls. D. permit A. think B. encourage C. help 5. Grand Canyon South Rim offers easy __ to the most beautiful viewpoints of the area. D. possession A. permission B. access location 6. The trip to explore Son Doong Cave is very __ It needs a lot of equipment and thorough preparation. D. threatened A. urgent B. charming C. risky 7. Kiwi birds and Hector s dolphins are some of the most signature __ of New Zealand. D. plant A. destination B. fauna C. flora 8. Conservationists announce that the giant pandas of China are an endangered __ D. series A. pieces B. species C. means 9. Tokyo has hidden gems like the Shinjuku Gyoen National Garden, a refuge teeming with diverse __ and fauna. D. trees A. plants B. flowers C. flora 10. Whale watching tours allow people to observe these giant mammals in their natural __ environment. D. marine A. land B. grassy C. desert 11. Some underwater caves near ancient Mayan ruins can only be explored through __ D. snorkeling A. windsurfing B. scuba diving C. sailing 12. You would look for a __ to learn more about things to do and places to st at a tourist attraction C. travel brochure D. daily newspaper A. science journal B. arts magazine 13. Rainforests are known for their incredible __ with millions of species of insects, birds, and plant all living together A. climate change B. biodiversity C. deforestation D. weather patterns 14. Many parts of Mongolia are covered in __ where horses and sheep roam freely D. grassland A. swamp B. jungle C. ice sheet 15. The Amazon rainforest is a complex __ with millions of plant and animal species depending on e other for survival. A. collection B. ecosystem C. territory D. landscape 16. The limestone formation of Thien Duong Cave is more __ than that of Phong Nha Cave. A. spectacular B. probable C. biological D. annual 17. Visitors to Grand Canyon National Park can hike, raft, or take a helicopter tour to __ the park's stunning landscape. A. discover B. locate C. consider D. explore 18. The worker asked the manager if he __ the promotion the following month. A. have received B. had received C. would receive D. will receive 19. She wondered whether I __ home late the night before. A. have come B. had come C. would come D. was coming

Here are the answers and explanations for the questions:<br /><br />**3. The best sightings of the northern lights often __ between 11pm and midingli.**<br /><br />* **B. occur** is the correct answer. "Occur" means to happen or take place, which fits the context of the sentence. <br /><br />**4. Tourists couldn't __ admiring the magnificent view of the Victoria Falls.**<br /><br />* **C. help** is the correct answer. The phrase "couldn't help" means to be unable to prevent oneself from doing something. <br /><br />**5. Grand Canyon South Rim offers easy __ to the most beautiful viewpoints of the area.**<br /><br />* **B. access** is the correct answer. "Access" means the ability to approach or enter a place.<br /><br />**6. The trip to explore Son Doong Cave is very __. It needs a lot of equipment and thorough preparation.**<br /><br />* **C. risky** is the correct answer. "Risky" means involving danger or the possibility of loss or failure.<br /><br />**7. Kiwi birds and Hector's dolphins are some of the most signature __ of New Zealand.**<br /><br />* **B. fauna** is the correct answer. "Fauna" refers to the animals of a particular region or period.<br /><br />**8. Conservationists announce that the giant pandas of China are an endangered __.**<br /><br />* **B. species** is the correct answer. "Species" refers to a group of living organisms consisting of similar individuals capable of exchanging genes or interbreeding.<br /><br />**9. Tokyo has hidden gems like the Shinjuku Gyoen National Garden, a refuge teeming with diverse __ and fauna.**<br /><br />* **C. flora** is the correct answer. "Flora" refers to the plants of a particular region or period.<br /><br />**10. Whale watching tours allow people to observe these giant mammals in their natural __ environment.**<br /><br />* **D. marine** is the correct answer. "Marine" refers to the sea or ocean.<br /><br />**11. Some underwater caves near ancient Mayan ruins can only be explored through __.**<br /><br />* **B. scuba diving** is the correct answer. "Scuba diving" is the activity of exploring underwater using scuba gear.<br /><br />**12. You would look for a __ to learn more about things to do and places to stay at a tourist attraction.**<br /><br />* **C. travel brochure** is the correct answer. "Travel brochures" are pamphlets or booklets that provide information about tourist destinations.<br /><br />**13. Rainforests are known for their incredible __ with millions of species of insects, birds, and plants all living together.**<br /><br />* **B. biodiversity** is the correct answer. "Biodiversity" refers to the variety of life on Earth.<br /><br />**14. Many parts of Mongolia are covered in __ where horses and sheep roam freely.**<br /><br />* **D. grassland** is the correct answer. "Grassland" is a large open area covered in grass.<br /><br />**15. The Amazon rainforest is a complex __ with millions of plant and animal species depending on each other for survival.**<br /><br />* **B. ecosystem** is the correct answer. "Ecosystem" refers to a community of living organisms and their physical environment.<br /><br />**16. The limestone formation of Thien Duong Cave is more __ than that of Phong Nha Cave.**<br /><br />* **A. spectacular** is the correct answer. "Spectacular" means impressive or magnificent.<br /><br />**17. Visitors to Grand Canyon National Park can hike, raft, or take a helicopter tour to __ the park's stunning landscape.**<br /><br />* **D. explore** is the correct answer. "Explore" means to travel through or around a place in order to learn about it.<br /><br />**18. The worker asked the manager if he __ the promotion the following month.**<br /><br />* **C. would receive** is the correct answer. This sentence uses the conditional tense to express a future possibility.<br /><br />**19. She wondered whether I __ home late the night before.**<br /><br />* **B. had come** is the correct answer. This sentence uses the past perfect tense to describe an action that happened before another past action. <br />