设随机变量X的分布函数为<imgwidth="36"height="21"v:shapes="_x0000_i1107"src="http://wljy.whut.edu.cn/uploadfiles/word/xxdsb07.files/image108.png">,下列结论中不一定成立的是()
①
<imgwidth="69"height="21"v:shapes="_x0000_i1108"src="http://wljy.whut.edu.cn/uploadfiles/word/xxdsb07.files/image132.png">
②
<imgwidth="73"height="21"v:shapes="_x0000_i1109"src="http://wljy.whut.edu.cn/uploadfiles/word/xxdsb07.files/image134.png">
③
<imgwidth="80"height="21"v:shapes="_x0000_i1110"src="http://wljy.whut.edu.cn/uploadfiles/word/xxdsb07.files/image136.png">
④
<imgwidth="36"height="21"v:shapes="_x0000_i1111"src="http://wljy.whut.edu.cn/uploadfiles/word/xxdsb07.files/image108.png">为连续函数