抗慢性心功能不全时强心苷的主要作用是
A．正性肌力作用
B．延长心房不应期
C．正性频率作用
D．降低自律性
E．加强心房与心室肌传导
参考答案：A
China will spend about 52 billion yuan _____ new airports and _____ old ones in the
west of China according to the 11th Five-Year plan. [ ]
A. repairing; building
B. to build; repair
C. building; repairing
D. to repair; build
助
