When the adverb 都dōu is used with a verb (都dōu + V) to refer to the object, object
pre-position is no longer an option but a must.
这两个人，我都不认识。
Zhè liǎng gè rén，wǒ dōu bú rèn shí 。
I don’t know either of these two people.
李：你喜欢喝茶还是(喜欢喝)咖啡？
Lǐ：Nǐ xǐ huān hē chá hái shì (xǐ huān hē) kā fēi？
Li: Do you like to drink tea or coffee?
丁：(茶跟咖啡，)我都喜欢。
Dīng ：(Chá gēn kā fēi, ) Wǒ dōu xǐ huān。
Ding: I like both (tea and coffee).
When 都 is used to refer to the subject, object pre-position becomes optional.
我和我妹妹都认识那个人。(= 那个人，我和我妹妹都认识。)
Wǒ hé wǒ mèi mèi dōu rèn shí nà gè rén。(= Nà gè rén，wǒ hé wǒ mèi mèi dōu rèn shí。)
Both my younger sister and I know that person.
[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.
