Te-form Sound Changes (音便): Why 書く Becomes 書いて, Not 書きて
The te-form itself is just “the connector form.” What makes it hard is the sound changes (音便, onbin) in Group 1 verbs: 書く becomes 書いて, 待つ becomes 待って, 死ぬ becomes 死んで. Learn the three patterns and the te-form stops being scary.
What Onbin Is
When Group 1 (う-verbs) take the te-form, the stem changes sound to make it easier to say. These shifts are called onbin (音便), “euphonic changes.” Group 2 (る-verbs) just drop る and add て (食べる → 食べて), so onbin is a Group 1 story.
The Three Patterns (by verb ending)
The Famous Exception
One verb refuses to follow its own group: 行く (to go). It ends in く, so you'd expect 行いて — but the real te-form is 行って (いって), using the 促音便 pattern.
It's the single exception worth memorizing outright, because 行く is so common.
How to Master It
- Group by ending sound (く/ぐ, う/つ/る, ぬ/ぶ/む, す) — not by individual verb.
- Say them out loud until 待って and 読んで feel automatic; the onbin exists to make speech smoother.
- Remember 行って as the one exception.
Teacher's Note
The te-form is the gateway to a huge amount of grammar (〜ている, 〜てください, 〜てもいい…). Drill the onbin patterns until they're reflexive — every hour you spend here pays back across dozens of later grammar points.
Make the te-form automatic
Nihongo Pass drills te-form conjugation in context with adaptive SRS — so the onbin patterns become second nature.
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