Here are some authentic expressions.Why not pick up and try some of these?

当一美国教师向你解释某个问题时，你如果连说两遍“i know”，我敢保证，他不会再跟你说什么了。用“i got it ”就顺耳得多，要是不懂就说“i’m not clear about it .”不过如果你会说“it’s past my understanding”或“it’s beyond me .”你的教师定会惊讶不已的.

Teachers normally asked,“Get it?" Then you replied, "Yes." or "No, I don't get it.".