​-따라가질 못하겠는데요.

  Sorry. I feel today class is so hard --> I don’t follow you.​

-말을 제대로 알아듣지 못했는데요.

  I can understand your mention exactly. --> I didn’t catch what you said.​

-이걸 영어로 뭐라고 합니까?

  How can I express this? ✔​​​