Sometimes it is desirable to connect a member both by riveting and welding. Which statement is TRUE concerning this procedure? （） ["Tearing through the member is more likely in this type connection","The weld may be broken by the stresses caused by riveting","The weld increases the tensile stress on the rivet heads","The welding must be completed before the riveting commence"]
型式读音正确的是（） ["がたしき","かたしき","こうしき","かし"]
某山谷在冬季有斑蝶类聚集过冬的情形。其中有数种青斑蝶，其幼虫以多种有毒植物为食，其毒素也在其体内积累。在同一栖息地还生存有一种斑风蝶，其斑纹与青斑蝶相似，但幼虫则以无毒植物为食。下列是某学生对青斑蝶和斑凤蝶的观察结果，错误的是（）。 ["青斑蝶的数量少于斑凤蝶","青斑蝶和斑凤蝶飞翔缓慢","各种青斑蝶会因相互拟态而彼此斑纹相似","青斑蝶色彩鲜艳"]
单置调车信号机处设几个进路选择继电器？各在何时励磁？
Oil water separators are used to ensure that ships dont discharge oil when pumping out （）. ["ballast water","boiler water","bilge water","sewage water"]
为什么要在交换5分钟后开始测量温度？
