She a student ten years ago, but she a teacher now.
A. is; was
B. was; is
C. was; was
答案:B
瀑布模型把软件生存周期划分为软件定义、软件开发与______三个阶段,而每个阶段又可分为若干更小的阶段。
坑道无线电波透视法综合曲线有哪几条构成?