—What does your sister usually do in the evening?

—She usually______ TV, but now she _____ a book. .

A．watch; read

B．watches; is reading

C．is watching; sees

D．watches; is seeing

准确地解决“软件系统必须做什么”是（）阶段的任务。

A．可行性研究

B．详细设计

C．需求分析

D．编码