TSUMUGU · TBCL 5 (est.) · 語法
之所以…，是因為…
grammar point · tier 2 · 之所以…是因為… (the reason X is, is because Y)
Names a result first, then supplies the cause behind it: the reason X holds is Y.
Hook inherited from 因為…所以… .
Names a result first, then supplies the cause behind it
框 · Frame
[subj] 之所以 [result]，是因為 [cause]
觸 · Trigger
An outcome is already on the table and you want to say what lies behind it.
序 · The move
1 name the subject, then 之所以 + the result already on view is the result known, the cause the new part?
2 是因為 + the cause that produced it does the cause answer 'why is that so'?
3 confirm the order: result first, cause second would 因為…所以… run cause-first instead?
例 · Examplesshown tap blur
1 他之所以the reason that 成功succeed ，是因為is because 堅持persist; hold on 和努力work hard 。
The reason he succeeded is his persistence and hard work.
界 · Boundary
因為…所以… 因為…所以… runs cause first, effect after, deriving the result. 之所以…是因為… runs result first, cause after, explaining a result already known. Same link, flipped order, and the cause is the new information.
是…的 是…的 frames one detail of a past event for focus. 之所以…是因為… frames a whole cause behind a stated result.
cause in the first bracket: 他之所以努力，是因為成功 → 他之所以成功，是因為努力
dropping 是: 他之所以成功，因為努力 → 他之所以成功，是因為努力
swapping in 所以: 他所以成功是因為努力 (stiff) → 他之所以成功，是因為努力
English 'the reason … is because …' maps cleanly, but learners reach for 因為…所以… and lose the result-first emphasis.