Illegal use of <when>-style tag without <choose> as its direct parent

报错信息：

javax.servlet.jsp.JspTagException: Illegal use of &lt;when&gt;-style tag without &lt;choose&gt; as its direct parent

<c:choose>
    <c:when test=”${people.age<18 }”>
        <h2>小于18</h2>
    </c:when>
    <c:when test=”${people.age=18 }”>
        <h2>等于18</h2>
    </c:when>
    <c:otherwise>
        <h2>大于18</h2>
    </c:otherwise>
</c:choose>