A: What are you doing here, Tom?
B: Playing games.
B: Why not?
A: You failed the exam, Tom. Could you tell me the reason?
B: I'm sorry.
A: Sorry? For what? You did not study hard?
B: No. The test was difficult, to say the least.
to say at the least：至少可以說
e.g. I was surprised at what he said, to say the least.
e.g. His conduct that evening was, to say the least, curious.
e.g. Her remarks were ill-advised, to say the least.
e.g. The appearance of Frank Cowperwood at this time was, to say the least, prepossessing and satisfactory.
Frank Cowperwood這個時候的相貌, 至少可以說是討人歡喜和令人滿意的。
be sorry for
e.g. I'm sorry for what I said; I never meant to insult you.
e.g. I'm sorry for taking it out on you.
e.g. They were sorry for the poor, especially for the dear little children.
e.g. In the midst of her own trouble Winifred was sorry for him.
其它：play a game：玩游戲
fail the exam：考試不及格