慢性阻塞性肺气肿主要引起
A.左心衰B.心肌炎C.Ⅰ型呼衰D.心包炎E.Ⅱ型呼衰
参考答案:E
假设可支配收入增加50美元,消费支出增加45美元,边际储蓄倾向是()。
A.0.05
B.0.10
C.0.90
D.1.00
Modern forms of transportation and communication have done much to ______ the isolation(隔离)
of life in Alaska. [ ]
A. break down
B. break out
C. break into
D. break through