写你发现学生把have been doing写成have been did,不是打叉,是红笔圈出did,在旁边写be动词+过去分词;写你给作文评语不用good,写This sentence shows you understand the difference between since and for;写你把典型错误剪下来贴成错题墙,学生课间围着猜哪个是自己的。批改是手术刀,不是盖章机。