In a simple positive descriptive statement, a degree adverb or a complement of degree should be used. When the degree adverb 很 is used, it does not literally mean ‘very’, but is only used to fulfil this basic grammar requirement.
我爸爸在大使馆工作，他很忙。
Wǒ bà bà zài dà shǐ guǎn gōng zuò，tā hěn máng。
My father works at the embassy. He is busy.
(Do not say 他忙 or 他是忙; 很 does not have a literal meaning of ‘very’ in this sentence.)
我累得要命。
Wǒ lèi dé yào mìng。
(要命 is a complement of degree; therefore, there is no degree adverb before 累.)
I am extremely tired. (= I am tired to death.)
When the adjective appears alone, a comparison is implied.
我有弟弟，也有妹妹。弟弟大，妹妹小。
Wǒ yǒu dì dì，yě yǒu mèi mèi 。dì dì dà ，mèi mèi xiǎo 。
I have a younger brother and I also have a younger sister. My younger brother is older
(than my younger sister).
王：你们学校，男老师多还是女老师多？
Wáng ：Nǐ men xué xiào ，nán lǎo shī duō hái shì nǚ lǎo shī duō ？
Wang: At your school, are there more male teachers or more female teachers?
丁：女老师多。
Dīng ：Nǚ lǎo shī duō 。
Ding: There are more female teachers.
Some adjectives are not associated with a matter of degree but are used to indicate a fact. The predicate in such a sentence is 是 + adjective + 的.
这件大衣是蓝的。
Zhè jiàn dà yī shì lán de 。
This coat is blue. (This is to indicate a fact.)
这件大衣很好看。
Zhè jiàn dà yī hěn hǎo kàn 。
This coat is pretty. (This is to indicate an opinion.)
王老师是男的还是女的？
Wáng lǎo shī shì nán de hái shì nǚ de ？
Is Teacher Wang a man or a woman?
(男 and 女 are adjectives, and it is improper to refer to individuals as 男人 or 女人.)
[1] Yip, P. C., Rimmington, D., Xiaoming, Z., & Henson, R. (2009). Basic Chinese: a grammar and workbook. Taylor & Francis.
[2] Teng, W. H. (2016). Yufa! A practical guide to Mandarin Chinese grammar. Taylor & Francis.
