In securing deck loads for an ocean tow，drill pipe should be（）. ["galvanized to protect against corrosion","held in place with heavy materials such as spare pendant wire","limited to no more than five courses high","provided with bulwarks at both ends of their bay"]
用于购买新设备所支出的资金或投资的成本，称之为（）。 ["资金成本","设备折旧","机会成本","材料成本"]
变电站主变过载时应如何消除过载？
以下关于细胞离子通道的描述，错误的是（） ["离子通道是由跨膜蛋白质构成的","离子通道是由外在蛋白质构成的","离子通道的运输具有一定的选择性","离子通道的运输只能顺电化学势梯度进行"]
采用ADC0809构成模拟量输入通道，ADC0809在其中起（）作用。 ["模拟量到数字量的转换","数字量到模拟量的转换","模拟量到数字量的转换和采样\/保持器","模拟量到数字量的转换和多路开关"]
简述清纱目的。
