数据模型通常有数据结构、数据操作和【 】3个要素组成。
参考答案:完整性约束
解析:数据模型通常有数据结构、数据操作和完整性约束3个要素组成。
根据首字母或汉语写出单词, 使句子意思完整。
1. The fifth day of a week is T_______.
2. She often c_______with her classmates about her school things.
3. I always get many nice p_______from my classmates on my birthday.
4. —How many d_______are there in a week?
—Seven.
5. You can find some i_______about Apple iphone 5 on the Internet.
6. Students should get everything _______(准备好的) for each class.
7. Look! Some young girls are playing _______(排球).
8. This pair of _______(运动)shoes is Kitty’s cousin’s.
9. The question is too _______(困难)for me, I can’t answer it.
10. We can get books from the school _______(图书馆).
据点工程的间距必须满足:一方面能充分发挥各据点的作用;另一方面必须保证两据点之间()。