设随机事件A与B相互独立,<imgwidth="118"height="21"v:shapes="_x0000_i1058"src="http://wljy.whut.edu.cn/uploadfiles/word/xxdsb06.files/image068.png">,则<imgwidth="77"height="21"v:shapes="_x0000_i1059"src="http://wljy.whut.edu.cn/uploadfiles/word/xxdsb06.files/image070.png">()