新概念英语第四册23课有5句难理解的句子现在请教下各位

(1)buttwoclassesmayberoughlyseen这句话书上解释为,可分为两为为什么这样解释呢?按照我们解释就是两类鸟粗略地能被看见!(2)AnyshithatcrossesthePacificisaccompaniedformanydaysbythesmalleralbatross,Whichmaykeepcompanywiththevesselforanhourwithoutvisibleormorethanoccasionalmovementofwing这句话是比较级句子吗?withoutvisibleormorethanoccasionalmovementofwing想了半天都不知道怎么解释?visibleormore(3)Thecurrentsofairthatthewallsoftheshipdirectupwards,aswellasinthelineofitscourse,areenoughtogivethegreatbirdwithitsimmensewingssufficientsustenanceandprogress这里的aswellas还有这里的with是不是表示附和的意思,也就是说给了这巨鸟,赋予了它巨大翅膀的浮力和推力?progress查了下字典似乎没有推力的意思(4)Itcomesnearertotheengineswithwhichmanhas'conquered'theair这里的with为什么放在主语之前是不是为了更好的修饰定语从句?(5)Ittiresnot,nordoesitboastofitspower这句话已经有动词了为什么还加个does,目的是想说明什么?