1) I am sorry but I just accepted another offer that I feel is more suitable to my needs / more right for me./ more interesting to me.

很抱歉，我剛接受了一個我認為更符合我需要的/更適合我的/更感興趣的工作。

2) I really appreciate your invitation, but I must decline it.

非常感謝你們的邀請，但我不得不謝絕。

3) Frankly speaking, I have been thinking that the work mode is not right for us after the discussion.

坦白地說，討論后我一直認為這個工作模式不適合我們。

4) I really think that position suits my education background better.

我真的覺得那個職位更適合我的教育背景。

5)I dont want to accept a position that I don’t think I will be happy in/offers me too little salary/ cant supply me with an apartment.

我不想接受一份我覺得不會讓我快樂的/一份薪水太少的/不能為我提供住房的工作。