高考中发挥好的英文表达可以包括以下几种：

鼓励性祝福

"Good luck on your exams!"

"Wishing you all the best on your exams. Good luck!"

表达信心

"You can do this. Best of luck."

"I know you'll do great!"

强调幸运

"It’s your lucky day."

简洁祝福

"Good luck."

"Do your best."

专业术语

"The national college entrance examination"

这些表达既地道又富有鼓励性，适合在高考这样的重要场合使用。希望这些建议能帮助你在高考中发挥出最佳水平。