经济发展是国家的核心部分。

Jīngjì fāzhǎn shì guójiā de héxīn bùfen.

Economic development is a core part of the country.

这个问题的核心是缺乏有效沟通。

zhège wèntí de héxīn shì quēfá yǒuxiào gōutōng.

The core of this problem is a lack of effective communication.

了解客户需求是销售工作的核心。

liǎojiě kèhù xūqiú shì xiāoshòu gōngzuò de héxīn.

Understanding customer needs is the core of sales work.