到底是哪面旗 孙老师您好：在小学六年下人教新版课本中有这样一句话The most important thing we did is that we learned to be good boys and girls.在这个句子中哪个是旗？为什么会有did和is？

,we did 这是定语从句,主句是The most important thing is that we learned to be good boys and girls.that we learned to be good boys and girls是表语以句课内详细讲解及大量练习