单项选择题
A.10sin 3tB.10sin 2tC.10sin 5tD.10sin t
A.E[X]=E[Y]B.E[XY]=0C.E[X]=0或E[Y]=0D.E[X]=0且E[Y]=0
A.(a-b)/2B.(a+b)2/12C.(a-b)2/12D.(a+b)/2