心源性哮喘表现为（）
A.夜间阵发性呼吸困难
B.端坐呼吸
C.呼气性呼吸困难
D.发作性喘息
E.劳力性呼吸困难
参考答案：A
Tony asked Mike ______. [ ]
A. where did he come from
B. where he comes from
C. where he came from
燃料层厚度是由什么决定的？
