【简答题】氢原子2p态(n=2, l=1)和3d态(n=3, l=2)精细结构裂距的比值为( )。
【简答题】已知曲线C: f(x)=x+ a x (a>0) ,直线l:y=x,在曲线C上有一个动点P,过点P分别作直线l和y轴的垂线,垂足分别为A,B.再过点P作曲线C的切线,分别与直线l和y轴相交于点M,N,O是坐标原点.若△ABP的面积为 1 2 ,则△OMN的面积为______.
【单选题】下列高程测量方法中,确定两点间高差的方法,不受地形条件限制,传递高程迅速,但精度低于水准测量的方法是( )
【简答题】如图,在平面直角坐标系中,⊙A与y轴相切于原点O, 平行于x轴的直线交⊙A于M、N两点,若点M的坐标是(-4,-2),过点N的双曲线是 ,则k=
【单选题】The photographs eokedstrong memories of our holiday inFrance
【单选题】What creates our memories?
A.
The whole mind and body.
C.
Sights and smells only.
【单选题】The Magic of Memory —By Laurence Cherry Our memories are probably our most cherished possessions. More than anything else we own, they belong uniquely to us, defining our personalities and our views o...
【简答题】已知椭圆C: x 2 4 + y 2 3 =1 的右焦点为F,左顶点为A,点P为曲线D上的动点,以PF为直径的圆恒与y轴相切. (Ⅰ)求曲线D的方程; (Ⅱ)设O为坐标原点,是否存在同时满足下列两个条件的△APM?①点M在椭圆C上;②点O为APM的重心.若存在,求出点P的坐标;若不存在,说明理由.(若三角形ABC的三点坐标为A(x 1 ,y 1 ),B(x 2 ,y 2 ),C(x 3 ,y 3 ...
【单选题】4 What creates our memories?
A.
The whole mind and body.
C.
Sights and smells only.