I. Read the passage. Choose the most suitable word to fill in the blank. Designated a UNESCO World Heritage site (1) _______ 2003, the remarkable Phong Nha-Ke Bang National Park contains the oldest mountains in Asia, formed approximately 400 (2) ________ years ago. Riddled with hundreds of cave systems - many of extraordinary scale and length - and spectacular (3) _______ rivers, Phong Nha is a speleologists’ heaven on the Earth. The Phong Nha region is changing fast. Son Trach village (population 3000) is the main centre, with an ATM, a growing range (4) _______ accommodation and eating options, and improving transport links with other parts of central Vietnam. The caves are the region’s absolute highlights, but the above-ground (5) ______ of forest trekking, the area’s war history, and rural mountain biking mean it deserves astay of around three days. 1. A. by B. on C. in D. from 2. A. millions B. million C. milions D. milion 3. A. underground B. under C. submarine D. underwater 4. A. of B. in C. on D. under 5. A. attraction B. attractions C. seeing D. seeings