一、单项填空 （共15小题；每小题1分，满分15分）
从A、B、C和D四个选项中，选出可以填入空白处的最佳选项。
1. _____ORBIS doctor who got here yesterday needed _______ X-ray machine to
examine his patients.
A. The; a B. The; an C. An; a D. An; an
2. —Oxfam trailwalkers in Hong Kong have to climb________ twenty hills and mountains.
—It’s really a tough hike.
A. through B. around C. over D. along
