瀑布模型的关键不足在于（）。
A.过于简单
B.各个阶段需要进行评审
C.过于灵活
D.不能适应需求的动态变更
参考答案：D
--- What do you think of teaching, Bob?
--- I find it and challenging. It is a job you are doing something serious but interesting.
A．funny, that
B．fun, that
C．fun, where
D．funny, which
第十一届北京亚运会的吉祥物是（）
A.团团
B.圆圆
C.盼盼
D.望望
