在英语中，描述留学上课时遇到的不同口音，可以使用以下表达：

Clear pronunciation:

"Can you please speak more clearly？"

Strong accent:

"He speaks with a strong American accent."

"She has a British accent."

Difficult to understand:

"I find it difficult to understand the instructor's accent."

Accent recognition:

"Can you repeat that sentence？ I'm still trying to get used to the accent."

Request for repetition:

"Could you say that again？ I want to make sure I got it right."

Asking for clarification:

"I'm not sure I understand. Could you clarify what you mean？"

Complimenting someone's accent:

"You have a very pleasant accent."

Asking for help with understanding:

"I'm struggling with this part. Could you help me with the pronunciation？"

以上表达可以帮助你在留学上课时与老师和同学有效沟通，并克服口音带来的障碍。