not at all,never mind,take it easy,don't mention it的用法及语境

1.没关系，单独用表示回答对不起
2.表示不介意别人去干什么
3.让对方放松，别紧张
4.回答谢谢的

Thank you - not at all
Would you mind if i open the windows - never mind
Oh lt is my turn ,i am afraid i will fail .- take it easy
Thanks for your help -don't mention it