1.
"\9" IE6/IE7/IE8/IE9/IE10都生效
"\0" IE8/IE9/IE10都生效，是IE8/9/10的hack
"\9\0" 只对IE9/IE10生效，是IE9/10的hack
2.
@media \0screen {body { background: red; }} 只对IE8有效
@media \0screen\,screen\9{body { background: blue; }} 只对IE6/7/8有效
@media screen\0 {body { background: green; }} 只对IE8/9/10有效
@media screen and (min-width:0\0) {body { background: gray; }} 只对IE9/10有效
