根据句意及首字母或汉语提示写出单词。

1. She never lost her b ____   in God.

2. The poor old man s____to death.

3. On our a____at the airport, we received a warm welcome.

4. Yao Ming is a very strong and e_____    basketball player.

5. Christmas is a r____festival in westem countries.

6.The children played a____(恶作剧)on their friends.

7.The girl____herself    (打扮)as a nurse.

8.They are building the stadium____(昼夜).

9.The children are _____   (玩得开心)each other in the park now.

10. They look after each other _____   (好像)they were sisters.

患者，女，20岁，诉自小牙齿不好，要求牙体美容。检查：全口牙齿均有有Ⅰ～Ⅱ度磨耗，牙冠均呈微黄色，釉质缺损较严重，牙本质暴露，探诊、温度测试均无明显反应。患者诉外祖母和母亲的牙齿也有类似的情况。最有可能是下列哪项病因？（）

A.遗传性疾病

B.幼时严重营养障碍

C.婴儿或母体疾病

D.幼时长期服用四环素类药物

E.夜磨牙