【单选题】
混凝土各种强度标准值之间的关系是（ ）
①
<imgwidth="23"height="24"v:shapes="_x0000_i1047"src="http://wljy.whut.edu.cn:80/uploadfiles/word/GCJG1.files/image038.gif">＞<imgwidth="27"height="24"v:shapes="_x0000_i1048"src="http://wljy.whut.edu.cn:80/uploadfiles/word/GCJG1.files/image040.gif">＞<imgwidth="21"height="24"v:shapes="_x0000_i1049"src="http://wljy.whut.edu.cn:80/uploadfiles/word/GCJG1.files/image042.gif">
②
<imgwidth="27"height="24"v:shapes="_x0000_i1050"src="http://wljy.whut.edu.cn:80/uploadfiles/word/GCJG1.files/image040.gif">＞<imgwidth="21"height="24"v:shapes="_x0000_i1051"src="http://wljy.whut.edu.cn:80/uploadfiles/word/GCJG1.files/image042.gif">＞<imgwidth="23"height="24"v:shapes="_x0000_i1052"src="http://wljy.whut.edu.cn:80/uploadfiles/word/GCJG1.files/image038.gif">
③
<imgwidth="27"height="24"v:shapes="_x0000_i1053"src="http://wljy.whut.edu.cn:80/uploadfiles/word/GCJG1.files/image040.gif">＞<imgwidth="23"height="24"v:shapes="_x0000_i1054"src="http://wljy.whut.edu.cn:80/uploadfiles/word/GCJG1.files/image038.gif">＞<imgwidth="21"height="24"v:shapes="_x0000_i1055"src="http://wljy.whut.edu.cn:80/uploadfiles/word/GCJG1.files/image042.gif">
④
<imgwidth="21"height="24"v:shapes="_x0000_i1056"src="http://wljy.whut.edu.cn:80/uploadfiles/word/GCJG1.files/image042.gif">＞<imgwidth="23"height="24"v:shapes="_x0000_i1057"src="http://wljy.whut.edu.cn:80/uploadfiles/word/GCJG1.files/image038.gif">＞<imgwidth="27"height="24"v:shapes="_x0000_i1058"src="http://wljy.whut.edu.cn:80/uploadfiles/word/GCJG1.files/image040.gif">