Lesson 5 of 8
Plain-form Lab — four more boxes, mostly free
about 10 minutes
After this lesson you can
- Derive the plain past of a verb from its te-form.
- Produce the plain negative and plain negative past of a known verb.
- Give the plain negative of ある and of a verb ending in う without applying the regular rule.
Words this lesson teaches
- かう
- to buy — plain negative かわない, not かあない
- ある
- there is (a thing) — plain negative is ない, on its own
- いる
- there is (a person or animal) — plain negative いない
- てつだう
- to help with something
- ならう
- to learn something from someone
- わすれる
- to forget (Group 2)
- かえる
- to go home (Group 1, despite ending in る)
- はこぶ
- to carry something over
What it explains
The past is the te-form with one vowel moved
て becomes た and で becomes だ. That is the entire rule, and it holds for every verb in the language including する and くる. のんで gives のんだ, かいて gives かいた, いそいで gives いそいだ. If you learned the te-form table, you have already learned the plain past table and nobody told you. This is why that lab came first.
The negative, and where the vowel comes from
Group 2 drops る and adds ない: たべる to たべない, わすれる to わすれない. Group 1 moves its last character to the あ row and adds ない: かく to かかない, のむ to のまない, はこぶ to はこばない. Group 3 is する to しない and くる to こない, and こない is worth saying out loud a few times because the vowel changes as well. The negative past is then the same move an い-adjective makes: ない comes off, なかった goes on. かかない gives かかなかった.
Two places the rule does not hold
A Group 1 verb ending in う does not go to あ. かう becomes かわない, てつだう becomes てつだわない, ならう becomes ならわない. The わ is left over from an older spelling and every う-verb has it. Separately, ある has no regular negative at all: it is simply ない. There is no あらない. いる is regular — いない — so the pair that has confused you since Foundations stays split here too.