Introducing themselves on social media platforms or in newspapers, some people writing in Chinese often start with 'we are a group of (我們是一羣 wǒmen shì yī qún)...'.
Whilst such opening is grammatical, the collective noun is unnecessary as it does not sound natural to Chinese ears, for the Chinese language places a premium on conciseness. The meaning of 'a group of' is inferred in the pronoun 'we'.
In a similar vein, the indefinite article is not required before an occupation in Chinese. Instead of wǒ shì yīgè yīshēng (我是一個醫生 I am a doctor), 'wǒ shì yīshēng'(我是醫生) suffices.