不要紧 的意思
1.可以是对不起后说it doesn't matter，意思是没关系。
也可以用在谢谢后面，意思是不客气，小事一件不值得挂牵。
回答my pleasure也可以用
matter
[英][?m?t?(r)][美][?m?t?]
n.
物质; 事件; （讨论、考虑等的）问题; 重要性;
vi.
要紧，重要; 化脓; 有重大影响; 有重要性;
A proton is an elementary particle of matter.
质子是物质的基本粒子。
Until the matter is resolved the athletes will be ineligible to compete.
除非这个问题得以解决，否则这些运动员没有资格参加比赛。
matter 短语
1.in the matter of
至于，关于，在…方面
the British are given pre-eminence in the matter of tea.
在用茶方面英国人享有杰出地位。
2
it is only a matter of time
只是时间问题；不会太久
it's only a matter of time before the general is removed.
离将军下台不会太久了。
3
a matter of
不超过（一段时间）
they were shown the door in a matter of minutes.
没过几分钟他们就被赶出了门。
it's a matter of working out how to get something done.
这关系到如何办成事的问题。
4
a matter of course
理所当然的事，必然的结果
the reports are published as a matter of course.
这些报告理所当然要出版。
5
a matter of form
手续问题，正确的程序
they must as a matter of proper form check to see that there is no tax liability.
作为应有的手续他们得检查且确保没有欠税。
6
a matter of record
they must as a matter of proper form check to see that there is no tax liability.
作为应有的手续他们得检查且确保没有欠税。
7
to make matters worse
更糟糕的是，更严重的是
8
what matter?
(英，旧)有什么要紧，有什么事
what matter if he was a Protestant or not?.
他是不是新教徒又有什么要紧？。