The adjective and the adverb 密切
The adjective 密切
密切 
is used to talk about relationships between people or connections between objects.
is used to talk about relationships between people or connections between objects.Examples
他们同意建立更密切的经济联系
They agreed to forge closer economic ties
tāmen tóngyì jiànlì gèng mìqiè de jīngjì liánxì
这两个国家一直保持着密切关系
The two countries have always maintained close relations
zhè liǎng ge guójiā yìzhí bǎochí zhe mìqiè guānxì
味觉和嗅觉有密切的联系
Taste and smell are closely related
wèijué hé xiùjué yǒu mìqiè de liánxì
密切 can also be a verb meaning “to bring together” when referring to relationships.
Examples
我们两个的性格十分不同，但这反而密切了我们两个的关系
Our nature is completely different, but it seemed to bring us closer together
wǒmen liǎng ge de xìnggé shífēn bù tóng, dàn zhè fǎn'ér mìqiè le wǒmen liǎng ge de guānxì
友好城市之间的交往密切了两国人民之间的友谊
The ties between their sister cities strengthened the friendship between the two nations
yǒuhǎo chéngshì zhījiān de jiāowǎng mìqiè le liǎng guó rénmín zhījiān de yǒuyì
The adverb 密切
As an adverb, 密切 is translated as “carefully”, “closely”.
Examples
医生密切地观察着妈妈病情的发展
The doctor is carefully monitoring the development of mother’s illness
yīshēng mìqiè de guānchá zhe māma bìngqíng de fāzhǎn
我们会密切注视任何进展
We will closely monitor any progress
wǒmen huì mìqiè zhùshì rènhé jìnzhǎn
要密切注视市场的动向
Market trends need to be closely followed
yào mìqiè zhùshì shìchǎng de dòngxiàng