【单选题】直线 的方向向量为 且过抛物线 的焦点,则直线 与抛物线围成的封闭图形面积为( )
【单选题】要了解全国的人口情况,则总体单位是( )。
【简答题】完形填空 What would I do for Carol's 50th birthday? It was __ 1 __ that she didn't want a party, certainly not a surprise party(that was an agreement at our marriage). 'How about a small dinner with __ 2 ...
【单选题】纯电感电路中电感上的电流与电压的相位关系是
【简答题】完形填空 What would I do for Carol’s 50th birthday? It was __ 1 __ that she didn't want a party, certainly not a surprise party (that was an agreement at our marriage). 'How about a small dinner with ...
【判断题】光电型接近开关利用被检测物体对红外线光束的遮光或反射作用,来检测物体的有无,被测物体不局限于金属,对所有能反射光线的物体均可检测。
【单选题】若直线 的方向向量为 ,平面 的法向量为 ,则
【单选题】光电型接近开关利用被检测物体对红外线光束的遮光或反射作用,来检测物体的有无,不易被测的物体为()。
【单选题】直线l的直线方程为ax+by+c=0,则该直线的方向向量为