1、essential

絕對必要的;必不可少的;基本的

It was absolutely essential to separate crops from the areas that animals used as pasture.

將莊稼和放牧區分開絕對必要。

As they must also sprint over short distances, speed is essential.

由于他們也必須進行短跑，因此速度至關重要。

基本的;本質的；根本的

Most authorities agree that play is an essential part of a child's development.

大多數權威人士都同意，玩耍在孩子成長過程中起著非常重要的作用。

In this trial two essential elements must be proven: motive and opportunity.

在這次審訊中，必須證明兩個基本因素：動機和時機。

（某學科的）基礎，基本知識

the essentials of everyday life, such as eating and exercise.

飲食、鍛煉等日常生活的要素

This has stripped the contest down to its essentials.

這就使比賽精簡到最基本的環節。

2、mission

(尤指赴他國的)使命，重要任務

Salisbury sent him on a diplomatic mission to North America.

索爾茲伯里派他到北美執行一項外交任務。

He has been on a mission to help end Lebanon's political crisis.

他已經被派執行一項旨在幫助結束黎巴嫩政治危機的使命。

駐外使團;出國代表團

the head of the mission in South Africa.

駐南非代表團團長

a senior member of a diplomatic mission.

外交使團的高級成員