<?xml version="1.0" encoding="UTF-8"?>

<!DOCTYPE teaching-plan SYSTEM "hr.dtd">

<teaching-plan>

<course>

<course-name>大学英语</course-name>

<class-hour>36</class-hour>

<exam-form>考试</exam-form>

</course>

<course>

<course-name>高等数学</course-name>

<class-hour>70</class-hour>

<exam-form>考试</exam-form>

</course>

<course>

<course-name>计算机应用基础</course-name>

<class-hour>108</class-hour>

<exam-form>上机考试</exam-form>

</course>

</teaching-plan>

<?xml version="1.0" encoding="UTF-8"?>

<!ELEMENT teaching-plan (course+)>

<!ELEMENT course(class-hour,exam-form)>

<!ELEMENT course-name(#PCDATA)>

<!ELEMENT class-hour(#PCDATA)>

<!ELEMENT exam-form(#PCDATA)>

dtd裏的第三行是故意少寫一個，想看看xml會不會報錯，但是沒反應 這是什麽原因啊老師