在软件过程模型中，不属于演化过程模型的是 （19） 模型。

A．增量

B．螺旋

C．线性顺序

D．并发开发

Directions:

A. Study the following picture carefully and write an essay of about 160--200 words.

B. Your essay must be written clearly on the ANSWER SHEET 2.

C. Your essay should meet the requirements below:

1) Describe the drawing,

2) interpret its meaning, and

3) point out its implications in our life.