用所给单词的适当形式填空。

1.  The doctor said _______( taste)  food is bad for students' health.

2. Laura told me that she _______(main) eats fruit and vegetables.

3.  Most people are in_______(agree)  that fruit and vegetables are good for health.

4.  Eating _______( burn)  barbecued meat often might cause cancer.

5. People who eat a _______ ( balance) diet should be healthier than those who only eat meat.

在下面列出的数据模型中，哪一个是概念数据模型 ( )

A) 关系模型
B) 层次模型
C) 网状模型
D) 实体、联系模型