一、用括号内所给词的适当形式填空。
1. One of the ______ (great) miracles(奇迹) is how the Great Wall was built.
2. The sun's ray can go ______ (direct) into the bedroom, so it's very bright.
3. The Great Wall was used ______ (keep) the enemy from invading (入侵).
4. Some ______ (history) think Stonehenge might be a burial place.
5. The building was built ______ (celebrate) a great victory.
6. Is the Great Pyramid one of the greatest ______ (mystery) in the world?
7. There are many famous ______ (history) places in Xi'an.
8. Stonehenge ______ (build) many, many centuries earlier than the priests' arriving in England.
9. The ______ (medicine) team worked tirelessly to save the lives of the injured.
10. We ______ (receive) five letters last week.

1. greatest 2. directly 3. to keep 4. historians 5. to celebrate 6. mysteries 7. historical 8. was built 9. medical 10. received