necessary

1. ADJ Something that is necessary is needed in order for something else to happen. 必要的

I kept the engine running because it might be necessary to leave fast. 我让发动机一直开着，因为可能需要快速离开。

Make the necessary arrangements. 做必要的一些安排。

2. ADJ A necessary consequence or connection must happen or exist, because of the nature of the things or events involved. 必然的[ADJ n]

Scientific work is differentiated from art by its necessary connection with the idea of progress. 科学工作不同于艺术在于它与进步的概念有必然联系。