so
⇒ 他迷恋于玩游戏，因此无心学习，成绩下降。
(Tā míliàn yú wán yóuxì, yīncǐ wú xīn xuéxí, chéngjì xiàjiàng.) He is obsessed with playing games, so he's not interested in studying and his achievementshave dropped off.
⇒ 这种病很容易复发，因此要格外注意。
(Zhè zhǒng bìng hěn róngyì fùfā, yīncǐ yào géwài zhùyì.) It's very easy to have a relapse with this kind of illness, so you have to be exceptionallycareful.
⇒ 由于引进了先进技术，生产效率因此大大提高。
(Yóuyú yǐnjìnle xiānjìn jìshù, shēngchǎn xiàolǜ yīncǐ dàdà tígāo.) The production rate has increased hugely due to imported advanced technology.