And which one is necessary的意思|示意

Zn is one of the necessary microelements for human body, which is important and helpful for well developed human body.

营养元素锌是人体必需的微量元素之一，对人体的生长发育起着重要的作用。

One thing that still bothers em about the design is the stained glass icons at the top of each window, which feels a little gimicky and quite cheesy - I do not feel that this is necessary.

这个设计里还有一个困扰我的事情就是那个装备窗口上方的彩色玻璃模样的图标，看上去像个不怎么高明的小把戏——我并不觉得这东西有存在的必要。

Zn is one of the necessary microelements for human beings, which is important and helpful for human body.

营养元素锌是人体必需的微量元素之一，对人体的生长发育起着重要的作用。

I liaise with the editorial team by text and email, so a lot can be done on the move, which is necessary as football will always be number one.

我都是靠自己的团队来编辑的，所以我做的工作不多。足球还是第一位的。

Shakespeare's play to contemporary drama is the first problem connected with them which confronts the historian of literature, and the only one he can treat with the necessary fullness.

莎土比亚戏剧和同时代戏剧的关系，是研究它们的文学史家所面临的首要问题，也是他唯一能够给以充分必要论述的问题。

The alteration of the past is necessary for two reasons, one of which is subsidiary and, so to speak, precautionary.

窜改过去所以必要，有两个原因。一个是辅助性的原因，也可以说是预防性的原因。