Question

you shouldn't arrive late

You shouldn’t arrive late for class．（改为祈使句）
___ late for class．

Answer 1

答案：Don't be 根据题意要把原句改为祈使句，原句为否定句形式变为祈使句时需要用到Don't引导的祈使句，此处be late for为迟到的意思，在Don't后接动词原形．故答案为：Don't be．