Which step is NOT generally taken when gas-freeing a tank?（）. ["Washing the tank interior with sea water","Application of degreasing solvents","Removal of corrosion products and sludge","Fresh air ventilatio"]
集拖装载时，集装箱被吊运至集拖位置上方（）处，暂停。 ["3mm","30mm","300mm"]
怎样拍摄剪影照片？
下列句子中，具有名词作状语表示所凭借的工具的是（）。 ["君为我呼入，吾得兄事之","项王、项伯东向坐，亚父南向坐","富贵不归故乡，如衣绣夜行","项羽召见诸侯将，入辕门，无不膝行而前"]
拱桥重力式桥墩与梁桥重力式桥墩相比较，具有（）等构造设施。
怎样才能检索到所需要的文献？
