北美洲的矿藏分布同地质构造有什么关系？
为什么高频淬火零件的表面硬度、耐磨性及疲劳强度均高于一般淬火？
The amount of expansion space to be left in a fuel tank when fuel oil is being received, is determined by the （）. ["quantity of fuel to be received","flash point of the fuel as it is received","fuel temperature as it is received","viscosity of the fuel being received"]
Gasoline vapor tends to collect（）. ["above the floor plates of the bilges","above the carburetor level","at the lowest point of the bilge areas","at no particular level"]
南北美洲和拉丁美洲是怎样划分的？
北美洲的地理位置有什么地理意义？
