鉴别心源性哮喘和支气管哮喘最有意义的是（）
A.端坐呼吸
B.血中BNP含量
C.干湿性啰音的多少
D.夜间呼吸困难
E.是否是受凉感冒后出现
参考答案：B
(74) is NOT served by building a prototype.
A．It takes the place of the final system
B．It is used as the foundation of the larger projects
C．It assists in estimating the cost of the project
D．It assists in gathering software requirements
灰分
