This unit and the next one deal with conjunctions (e.g. 因为yīn wéi …所以suǒ yǐ , 但是 dànshì) and conjunctives (e.g. 就 jiù, 才 cái, 却 què) which link clauses together in compound sentences. A conjunction may occur in the first or second clause and may be placed either before or immediately after the subject/topic whereas a conjunctive, which is in fact a referential adverb functioning as a link word, may only occur in the second clause and it must be placed immediately before the predicate/comment:
Yīn wéi zuó tiān xià yǔ ，suǒ yǐ yùn dòng huì zàn tíng 。
Because it rained yesterday, the sports meeting was (therefore) postponed.
(因为yīn wéi ‘because’ and 所以suǒ yǐ ‘therefore’ are both conjunctions.)
If the subject/topic or the object of the two linked clauses is the same, it is usually omitted in the second clause:
（Yīn wéi）tā pǎo dé hěn kuài ，suǒ yǐ dé le dì yī 。
Because she ran very fast, (therefore) she came first.
（Yīn wéi ）nǐ bú xǐ huān chī píng guǒ ，suǒ yǐ wǒ méi mǎi 。
Because you don’t like apples, (therefore) I didn’t buy any.
 Yip, P. C., Rimmington, D., Xiaoming, Z., & Henson, R. (2009). Basic Chinese: a grammar and workbook. Taylor & Francis.