数据库管理系统(DBMS)提供数据定义语言(DDL)及它的翻译程序，DDL

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问题填空题

数据库管理系统(DBMS)提供数据定义语言(DDL)及它的翻译程序，DDL定义数据库的模式、外模式和内模式，并通过翻译程序分别翻译成相应的目标模式，存放在【1】。

答案

参考答案：系统目录/数据字典/DD

阅读理解

阅读理解。

Christmas (圣诞节) is December 25. It's the most important holiday in America.

People like to send Christmas cards to their friends and they buy gifts for their family and friends before

Christmas.

Christmas Day is a day for family reunion (团聚). The family come together and sit down to have a meal

in the afternoon. On Christmas Day people go to church (教堂) to listen to Christmas Carols (颂歌). Children

are very happy on that day, and they can get a lot of gifts.

1. ________ is the biggest festival in America.

A. Christmas

B. New Year

C. Thanksgiving Day

D. Teachers' Day

2. Many people can get some ________ before Christmas.

A. work

B. cards

C. new clothes

D. cards or gifts

3. The family often have ________ together in the afternoon on Christmas Day.

A. a meeting

B. a meal

C. a ball

D. match

4. Children like Christmas Day very much, and they can ________.

A. get many gifts

B. watch TV all day

C. sing Christmas songs

D. go to the concert

5. Children like Christmas Day very much, and they can ________.

A. get many gifts

B. watch TV all day

C. sing Christmas songs

D. go to the concert

填空题

弯曲时，板料的最外层纤维频于拉裂时的弯曲半径称为（）。