设随机变量<imgwidth="19"height="17"v:shapes="_x0000_i1025"src="http://wljy.whut.edu.cn/uploadfiles/word/xxdsb10.files/image002.png">的期望和方差相等,则<imgwidth="19"height="17"v:shapes="_x0000_i1026"src="http://wljy.whut.edu.cn/uploadfiles/word/xxdsb10.files/image002.png">不能服从()