Verb + と — the when/if conditional (自然と条件)
Pattern
Section titled “Pattern”[verb dictionary form] + と = “when / if” — a natural, inevitable consequence. When X happens, Y automatically follows.
- 呼吸すると肺に取り込まれる = when we breathe, [oxygen] is taken into the lungs (automatic consequence)
- 春になると花が咲く = when spring comes, flowers bloom (natural law)
- ボタンを押すとドアが開く = if you press the button, the door opens (mechanical)
What と-conditional is for
Section titled “What と-conditional is for”と after a verb in dictionary form marks a natural/automatic consequence:
- Habitual/general truth — when X happens, Y always happens: when spring comes, flowers bloom
- Mechanical/inevitable result — if X, then Y follows automatically: press button → door opens
- Discovery/sequence (in narratives): opened the door and (found that)…
Key: the result is NATURAL, AUTOMATIC, or INEVITABLE — not a choice.
The four conditionals (compare)
Section titled “The four conditionals (compare)”| Conditional | Use | Example |
|---|---|---|
| と (dictionary + と) | natural consequence, inevitable | 呼吸すると = when we breathe |
| たら (past + ら) | if/when — general, after X happens | 行ったら = if/when I go |
| ば (ば-form) | if — conditional requirement | 行けば = if I go |
| なら (dictionary + なら) | if [that’s the plan] — premise-based | 行くなら = if you’re going |
と vs たら: と = automatic/natural (can’t be a personal choice); たら = more flexible (can express “after”, “if”, personal decisions).
- 春になると花が咲く ✓ (と — natural law)
- 春になったら花見に行く ✓ (たら — personal plan, NOT と — と can’t express intention/choice)
RULE: if the result involves a PERSONAL CHOICE or INTENTION, use たら/ば/なら — NOT と.
Structure note
Section titled “Structure note”- と attaches to the dictionary form (present): する + と, なる + と, 押す + と
- The subordinate clause keeps its own subject with が: 私たちが呼吸すると = “when WE breathe”
酸素は私たちが呼吸すると肺の中に取り込まれる。
= “Oxygen is taken into the lungs when we breathe.” — the breathing automatically causes the absorption → と (natural consequence).
Why not たら? たら would imply the result is a choice/eventuality — but oxygen absorption is automatic. と = the natural-law reading.
Source
Section titled “Source”Ebot lesson 2026-08-29: 酸素は私たちが呼吸すると肺の中に取り込まれる — user noted “(する + と = when/if) is new to me”. Dedicated page created for the と-conditional.