“高考加油”用英语可以这样说：

1. "Good luck with the Gaokao!"

（这是最直接、常用的表达方式。）

2. "Wish you success in the Gaokao!"

3. "All the best for your Gaokao!"

4. "You can do it! Good luck on the Gaokao!"

5. "Stay confident and do your best in the Gaokao!"

如果你想更正式或更有鼓励性，可以说：

"We believe in you and wish you great success in the Gaokao."

"Best of luck in your Gaokao exam. You've got this!"

这些表达都可以用来鼓励正在准备高考的学生。