根据句意，用括号中所给词的适当形式填空。

1. The pretty girl              the first prize in yesterday's singing competition. (win)

2. It rained yesterday.            , I took an umbrella. (lucky)

3. The fish can't live             water. (with)

4. Many             come to China every year all over the world. (visit)

5. She is an             girl because she could swim when she was four. (usual)

在教学过程中，教师为了让学生掌握知识的本质意义，需要变换知识的呈现方式，其中本质属性保持恒在，而非本质属性可有可无，这在心理学中称为( )

A．变式

B．比较

C．概括

D．抽象