简述纵骨架式舷侧结构的优点。
五站更换南线滤机出酸平衡管，要关闭南线上酸蝶阀，关南线（）进酸阀。 ["加热器","结晶","硅藻土","高位槽"]
将鼠标指向窗口的（）并拖动它，可以改变窗口的大小。 ["边框","菜单栏","标题栏","滚动条"]
简述冲击式汽轮机级的工作原理和级内能量转换过程及特点。
Cast iron pistons used in large propulsion diesel engines are constructed with （） ["not taper what so ever","the skirt being tapered and smaller than the crown","the skirt being tapered and larger than the crown","the crown being tapered and smaller than the skirt"]
前期物业服务合同内容是否应该订入物业买卖合同？
