1.ie7下，下面的背景图不起作用
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<img style="display: none" id="code_img_closed_356fbcea-0c4f-4b4d-8082-5b464d5bdd33" class="code_img_closed" src="https://www.jb51.cc/res/2019/02-07/12/1c53668bcee393edac0d7b3b3daff1ae.gif" alt=""><img id="code_img_opened_356fbcea-0c4f-4b4d-8082-5b464d5bdd33" class="code_img_opened" onclick="cnblogs_code_hide('356fbcea-0c4f-4b4d-8082-5b464d5bdd33',event)" src="https://www.jb51.cc/res/2019/02-07/12/405b18b4b6584ae338e0f6ecaf736533.gif"><span class="cnblogs_code_collapse">代码
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