下列哪项可导致吸气性呼吸困难（）
A.急性喉炎
B.支气管哮喘
C.喘息性慢性支气管炎
D.慢性阻塞性肺气肿
E.左心功能不全
参考答案：A
Your phone ______ for several minutes now. Why don’t you answer it?
A．had rung
B．rang
C．has been ringing
D．was ringing
In which form of projects origination would the project manager be likely to exercise the most control over Project resources.（）
A.Strongmatrix
B.Projectized
C.Projectcoordinator
D.Weakmatrix
