ていく— As Time Goes On / Going Away Doing

• 少しずつ日本語が上手になっていく。

  Sukoshi zutsu nihongo ga jouzu ni natte iku.

  My Japanese will gradually get better (going forward).

  なって + いく = becoming, the change heading away from now into the future

• 彼は手を振りながら去っていった。

  Kare wa te o furinagara satte itta.

  He waved and walked away.

  去って + いった = went off (physical movement away from the speaker)

• これから物の値段が上がっていくと思います。

  Kore kara mono no nedan ga agatte iku to omoimasu.

  I think prices will keep going up from now on.

  上がって + いく = rising, the change heading away from now into the future

• ・Key Concept: ていく (movement/change away, toward the future) vs てくる (movement/change toward, up to now): 寒くなっていく (it will keep getting colder from now on) vs 寒くなってきた (it has been getting colder up to now).

Commonly confused with

The JLPT rarely asks whether you recognise a pattern — it asks which of several similar patterns fits. These are the ones ていく is tested against.

• Potential Form — Can / Be Able To (Verbs)
• がる／がっている — Describing Others' Feelings
• 〜出す (だす) — Abrupt Eruptions
• 〜始める (はじめる) — Intentional Beginnings
• 意向形 (いこうけい) — Volitional Form (Let's / I'll)
• くする / にする — Make something become (a quality)
• ながら — While doing (simultaneous actions, same subject)
• ないで — Without doing / Instead of doing