97免费在线观看视频,亚洲综合自拍网,黄色毛片免费观看,热久久综合网,免费看日产一区二区三区 狠狠操av,久久久涩涩涩,在线精品免费视频,人人插天天干,久久91精品国产91久久

單項選擇題

A cofferdam is().

A.any deck below the main deck and above the lowest deck
B.a member that gives fore-and-aft strength
C.made by placing two bulkheads a few feet apart
D.a heavy fore-and-aft beam under the deck

微信掃碼免費搜題