core

1. N-COUNT The core of a fruit is the central part of it that contains seeds. 核

Someone threw an apple core. 有人扔了一个苹果核。

2. N-COUNT The core of an object, building, or city is the central part of it. 中心[usu with poss]

...the Earth's core. …地核。

3. V-T If you core a fruit, you remove its core. 去核

...machines for peeling and coring apples. …苹果削皮去核机。

4. N-SING The coreof something such as a problem or an issue is the part of it that has to be understood or accepted before the whole thing can be understood or dealt with. (问题的) 核心

...the ability to get straight to the core of a problem. …直击问题核心的能力。

5. ADJ A core team or a core group is a group of people who do the main part of a job or piece of work. Other people may also help, but only for limited periods of time. 核心 (团体)

We already have our core team in place. 我们的核心队伍已经就位。

6. ADJ In a school or college, core subjects are a group of subjects that have to be studied. 必修的 (课程)

The core subjects are English, mathematics and science. 必修课程为英语、数学和科学。

I'm not opposed to a core curriculum in principle, but I think requiring a foreign language is unrealistic. 原则上我不反对必修课程，但是我认为把外语列为必修课是不现实的。

7. N-SING The core businesses or the core activities of a company or organization are their most important ones. 核心 (工作或活动)

The core activities of social workers were reorganized. 社工的核心工作被重新安排了。