He, out of breath, _____ himself along the street. Perhaps he was badly ill. [ ]

A. drew

B. pulled

C. dragged

D. pushed

集中器、采集器应可与多种标准通信单元匹配，完成数据采集的各项功能。集中器、采集器应满足与通信单元直接交互命令响应时间不大于（）

A.5s

B.6s

C.8s

D.10s