如题
<!DOCTYPE html>
<html lang="en">
<head>
<meta charset="UTF-8">
<link rel="stylesheet" href="https://cdn.bootcss.com/bootstrap/3.3.7/css/bootstrap.min.css">
<script src="https://cdn.bootcss.com/jquery/1.12.4/jquery.min.js"></script>
<script src="https://cdn.bootcss.com/bootstrap/3.3.7/js/bootstrap.min.js"></script>
<link rel="stylesheet" href="{{ url_for('static',filename='css/base.css') }}">
{% block head %}{% endblock %}
<title>{% block title %}{% endblock %}-知乎数据库</title>
</head>
<body>
<nav class="navbar navbar-default">
<div class="container">
<div class="navbar-header">
<img style="width:120px;height:44px" src="{{ url_for('static',filename='images/zhihu6.png') }}" alt="">
<button type="button" class="navbar-toggle collapsed" data-toggle="collapse"
data-target="#bs-example-navbar-collapse-1" aria-expanded="false">
<span class="sr-only"></span>
<span class="icon-bar"></span>
<span class="icon-bar"></span>
<span class="icon-bar"></span>
</button>
</div>
<!-- Collect the nav links, forms, and other content for toggling -->
<div class="collapse navbar-collapse" id="bs-example-navbar-collapse-1">
<ul class="nav navbar-nav">
<li class="active"><a href="/">首页<span class="sr-only">(current)</span></a></li>
<li><a href="{{ url_for('question') }}">发布问题</a></li>
</ul>
<form class="navbar-form navbar-left" action="{{ url_for('search') }}">
<div class="form-group">
<input name="q" type="text" class="form-control" placeholder="请输入关键字">
</div>
<button style="background-color:#337ab7;color:#FFFFFF" type="submit" class="btn btn-default">
<span class="glyphicon glyphicon-search" aria-hidden="true"></span> Search
</button>
</form>
<!--<img style="width:400px;height:45px;" src="{{ url_for('static',filename='images/logo4.png') }}" alt="">-->
<ul class="nav navbar-nav navbar-right">
{% if username %}
<li><a style="color: #0084ff;background: rgba(0,132,255,.1);border-color: transparent;"
href="{{ url_for('user',id=0) }}"><span class="glyphicon glyphicon-user" aria-hidden="true"></span> {{username}}</a></li>
<li><a href="{{ url_for('logout') }}"><span class="glyphicon glyphicon-remove-sign" aria-hidden="true"></span> 注销</a></li>
{% else %}
<li><a style="color: #0084ff;background: rgba(0,132,255,.1);border-color: transparent;"
href="{{ url_for('login') }}"><span class="glyphicon glyphicon-user" aria-hidden="true"></span> 登录</a></li>
<li><a href="{{ url_for('regist') }}"><span class="glyphicon glyphicon-plus-sign" aria-hidden="true"></span> 注册</a></li>
{% endif %}
</ul>
</div><!-- /.navbar-collapse -->
</div><!-- /.container-fluid -->
</nav>
<div class="main">
{% block main %}{% endblock %}
</div>
</body>
</html>
问题出现在这个{% block head %}{% endblock %}你的模板不知道是什么，只能当作一个文本输出来了，你起码给它放到标签里呀，一般head里面要么写的是标题，关键字，描述，（js和css引入）除此之外不知道你这个又是代表了什么含义
像是Django的模板，模板不能直接双击运行访问的，会直接显示源代码，需要Django编译，通过http协议访问对应的路由后才能看到需要的内容