单词拼写。

     根据下列各句句意和空白之后的汉语提示词，在横线上写出对应单词的正确形式，每空只写一词。

1. We all know that he is too ________ (顽固) to apologize.

2. When the boiler ________ (爆炸) many people were hurt by the steam.

3. The scientists have made a ________ (有价值的) discovery recently. 

4. More than 10,000 ________ (运动员) took part in the 29th Olympic Games in Beijing in 2008.

5. He ________ (承认) having killed his wife. So he was sentenced to death.

6. Many people are going to serve as ________ (志愿者) in the Guangzhou Asian Games. 

7. What he's bought for me is ________ (正是) what I have been looking forward to. 

8. In most maths examinations senior high school students are allowed to use ________ (计算器)

   in the exams.

9. My uncle is grateful to me for________ (说服) him into giving up smoking.

10. At first, I thought these flowers were real, but they are ________ (人造的).