标准规格CCC标志按尺寸大小可分为（） ["A.3种","B.4种","C.5种","D.6种"]
The stability of a vessel is normally the greatest when all fuel and water tanks are full because the （）. ["center of gravity is lowered","center of buoyancy is lowered","reserve buoyancy is unchanged","hull freeboard is increased"]
为改善过共析钢的切削加工性，应采用（） ["完全退火","去应力退火","球化退火","均匀化退火"]
斯堪的纳维亚三国在经济发展上有哪些共同点？
亚共析钢常用的退火方法是（） ["完全退火","球化退火","等温退火","均匀化退火"]
要坚持低焦高档发展方向，高度重视低焦油品牌的市场培育，加大（）的培育力度。
