给词语排序，并写出理由。

1．博士生  小学生  大学生  硕士生  中学生

     排序：                                                                                                 

     理由：                                                                                                 

2．儿子  曾祖父  父亲  祖父

     排序：                                                                                                 

     理由：                                                                                                 

3．国庆节  儿童节  劳动节  建军节  植树节

     排序：                                                                                                 

     理由：                                                                                                 

4．西安  中国  东亚  陕西  亚洲

     排序：                                                                                                 

     理由：                                                                                                

下列哪项最适宜作烤瓷贴面修复（）

A.严重唇向位上前牙

B.反牙

C.重度四环素牙

D.轻、中度着色牙

E.严重深覆的下前牙