Yě(也) gèng(更) hái(还) yòu (又)
These adverbs all can be translated as “also” in English when employed in compound sentences. They are sometimes interchangeable, but they differ in their ways of connection and usages.
The two parts of the compound sentence connected by yě(也) can share the same subject or two different subjects, and yě(也) can appear in both parts or only the latter part of the compound sentence. The two parts of the compound sentence linked by yě(也)are of parallel relation, which means they can be transposed without changing the meaning of the expression.
wǒ (yě )xǐ huān chàng gē, yě xǐ huān tiào wǔ.
I like singing, I also like dancing.
wǒ xǐ huān chàng gē, tā yě xǐ huān chàng gē.
I like singing, he likes singing, too.
Yòu (又) is generally used to indicate a repetition of a person’s same action or situation, therefore, the two parts of the compound sentence share the same subject.
tā zuó tiān lái le, jīn tiān yòu lái le.
She came yesterday, and she’s here today.
Also, yòu (又) usually forms the pattern yòu (又)…yòu (又)…which indicates the simultaneous existence of two actions or situations. It can be used for both verbs and adjectives, The structure yòu (又) Adj1 yòu (又) Adj2 is used to describe two qualities of the same person or the same thing.
hái zǐ men yòu chàng yòu tiào.
The children sang and danced.
zhè gè fáng jiān yòu xiǎo yòu pò ,de què bú shì hé zhǎng qī jū zhù.
This room is small and broken, it's really not suitable for long-term living.
Yě(也) and yòu (又) can be interchangeable in some contexts when they both have the same subject in the compound sentence.
tā shì wǒ de tóng xué ,yě /yòu shì wǒ de shì yǒu.
He is my classmate, and also my roommate.
The use of hái(还) in a compound sentence usually has the effect of stressing the additional information provided by the latter part of the compound sentence, therefore, the two parts of the compound sentence are of progressive relation and must share the same subject.
wǒ xǐ huān chàng gē ,hái xǐ huān tiào wǔ.
I like singing, and I also like dancing.
chú le yī zhāng xīn de chuáng , wǒ men hái xū yào yī zhāng xīn de zhuō zǐ.
Besides a new bed, we also need a new table.
Compared with hái(还), the adverb gèng(更) not only introduces but also emphasizes the additional information to what has been stated previously. In other words, the situation following gèng(更) is of greater impact or degree of importance. The two parts of the compound sentence connected by gèng(更) can share the same subject or two different subjects
nǐ shì wǒ de péng yǒu, gèng shì wǒ de jiā rén.
You are more than a friend, you are also my family.
zhè jiàn shì tā bú zài hū, wǒ gèng bú zài hū le.
Even he doesn’t care about this matter, much less do I.
the same subject