先通读下面的短文，掌握其大意，然后根据短文内容和所给首字母，在空格内填入一个适当的词，使短文意思完整。所填单词在题后横线上必须完整写出。 (本大题共5分，每格0.5分)

The flying fox is not a fox at all. It is an extra large bat（蝙蝠）that has got a fox’s head, and that feeds on fruit i   小题1:   of insects. Like all bats, flying foxes hang themselves by their toes when at rest, and t 小题2:   in great groups when out flying. A group will l   小题3:  in one place for years. Sometimes several hundreds of them occupy（占据）a tree. As they return to the tree toward sunrise, they quarrel a  小题4:   themselves and fight for the best places until long after daylight.

Flying foxes have b    小题5:   once a year, giving birth to only one at a time. At first the mother has to c 小题6:  the baby on her chest wherever she goes. Later she l 小题7:   it hanging up, and brings back food for it to eat. Sometimes a baby bat falls down to the g 小题8:   and squeaks（尖叫）for help. Then the older ones swoop（俯冲） down and try to pick it up. If they f  小题9:    to do so, it will die. Often hundreds of d 小题10:    baby bats can be found lying on the ground at the foot of a tree..

原型化方法是对预先定义方法的补充，它的提出基于若干前提和条件，下述( )不在这些前提和条件之列。

A．需求难以事先严格定义

B．存在快速建造原型的工具

C．有实际存在的系统原型

D．开发可一次完善不需反复