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

()of the following conditions will cause a vessel’s bottom to be subjected to tension stresses.

A.Concentration of weight aft
B.Concentration of weight forward
C.Concentration of weight amidships
D.Concentration of weight at both ends of the vessel

微信掃碼免費搜題