Question

Come to school early（改成否定句）？

Answer 1

这是一个祈使句，要把它改成否定句的话，需要借助助动词，那么就应该是don't
come to school early.

Answer 2

祈使句改否定句，直接句子前面加Don't即可。Don't come to school early.不要早到学校。