经检查，诊断明确后，首选的治疗是
A. 抗感染加体位引流
B. 纤维支气管镜吸痰
C. 支气管舒张药治疗
D. 雾化吸人治疗
【B20】
A. late
B. back
C. ready
D. about
某工程双代号时标网络计划下图所示，其中工作A的总时差和自由时差()天。
A. 分别为1和0
B. 均为1
C. 分别为2和0
D. 均为0
Which of the following is not the reason why companies have begun to shift their attention
A. the constant improvement of economy in the US.
B. the demand of experienced and well-trained employees.
C. the demonstration of its market strength indicator.
D. the possible lack of workforce in the near future.
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