以下哪个指标不是判断行业生命周期的指标（） ["需求增长率","产品品种数","竞争者的竞争方法","进入（或退出）行业的障碍"]
额定电流是指风力发电机组在（）下运行的电流。 ["额定功率","额定电压","频率","发电率"]
美国强生产品公司将婴儿洗发精这一产品推向成年人市场，这属于哪一种战略（）。 ["市场调查战略","市场渗透战略","市场垄断战略","市场开发战略"]
什么是编码？什么是解码？
To maintain design discharge pressure from a centrifugal pump, the design clearance must be maintained between the （）. ["shaft and impeller","motor and pump shaft","casing and impeller wearing rings","lantern ring and impeller"]
简述砖砌条形基础的组成。
