星级典句：
第一句：Please don't blame yourself.
别自责了。
A: I'm terribly sorry that I made such a mistake.
我对自己犯这样的错误感到十分抱歉。
B: It doesn't matter. Please don't blame yourself.
没关系，别自责了。
第二句：It doesn't matter.
没关系。
A: I'm sorry I forget to bring you the book.
很抱歉我忘了给你带书了。
B: It doesn't matter.
没关系。
A: I'll bring it next time I see you.
下次见你时我给你带上。
B: OK.
好的。
其他表达法：
I quite understand.
我很理解。
This can happen to the best of us.
这种事谁难免。
It't not your fault.
这不是你的错。