ADJ-GRADED 必不可少的;不可或缺的 If you say that someone or something is indispensable, you mean that they are absolutely essential and other people or things cannot function without them. 必不可少的;不可或缺的
She was becoming indispensable to him. [+ to]
他已变得越来越离不开她了。
...the indispensable guide for any traveller in France.