目前工程机械使用的发动机大多是（）冲程柴油发动机。 ["1","2","3","4"]
日本现有广告公司4500多家，其中排名第一的（）广告公司同时也是世界排名第一的广告公司，几年来其年营业额一般在（）日元左右。
安全阀的选用应当符合（）要求。 ["安全阀适用于清洁、无颗粒、低粘度的流体","全启式安全阀适用于排放气体、蒸汽或者液体介质","微启式安全阀一般适用于排放液体介质","排放有毒或者可燃性介质时必须选用封闭式安全阀"]
隧道净空收敛一般采用（）监测。 ["A、收敛计 ","B、测斜仪 ","C、铟钢尺 ","D、应变计"]
Which of the following can lead to the contribution of LAN traffic congestion?（） [" Too many hosts in a broadcast domain"," Full duplex operation"," Broadcast storms"," Multicasting"," Segmentation"," Low bandwidth"]
什么是现金流入量、现金流出量、净现金流量？
