……，因而……: therefore, hence (written)
【五50】复句 / complex sentences
Tone colorsā tone 1á tone 2ǎ tone 3à tone 4a neutral
因而 introduces a result that follows from the preceding clause: “hence”, “therefore”, “as a result”. It is a written word (reports, articles, minutes, an expert's explanation); in conversation you would say 所以.
It sits at the start of the second clause, after the cause, and the subject is often not repeated there: 她按时完成了任务，因而受到了表扬. Unlike 因此, it rarely opens a new sentence.
Place it among its neighbours: 所以 (spoken, neutral), 因此 (written, can also open a sentence), 因而 (written, welds the result to the cause in one sentence) and 从而 (the result is obtained by means of what precedes, or it is an aim: 通过……，从而……).
Examples
他病了，因而没来上课。
Tā bìng le, yīnér méi lái shàngkè.He was ill, and therefore did not come to class.
天气越来越冷，因而感冒的人多了起来。
Tiānqì yuè lái yuè lěng, yīnér gǎnmào de rén duō le qǐlái.The weather is getting colder and colder, so more and more people are catching colds.
她按时完成了任务，因而受到了表扬。
Tā ànshí wánchéng le rènwu, yīnér shòudào le biǎoyáng.She finished the task on time and was therefore praised.
这家医院的医生经验丰富，因而每天都有很多病人专门来看病。
Zhè jiā yīyuàn de yīshēng jīngyàn fēngfù, yīnér měitiān dōu yǒu hěn duō bìngrén zhuānmén lái kànbìng.The doctors at this hospital are very experienced, so every day many patients come specially to be seen.
他长期坐着工作，缺少运动，因而得了腰疼的毛病。
Tā chángqī zuò zhe gōngzuò, quēshǎo yùndòng, yīnér dé le yāo téng de máobìng.He has long worked seated and gets too little exercise, and as a result he developed back trouble.
Common mistakes
✗ 因而他没来上课，他病了 → ✓ 他病了，因而没来上课 (the cause first, 因而 introduces the result).
✗ 太累了，因而我们回家吧 → ✓ 太累了，所以我们回家吧 (因而 reports a fact; to lead into a suggestion, use 所以).