高い・
An い-adjective makes its own "not" and "was": the final い changes. です after it only adds politeness.
How to form it
高い → 高くない・高かった・高くなかった
です after any of them makes it polite. Before a noun it goes straight on: 高い本.
One exception
いい → よくない・よかった・よくなかった
いい (good) is the only irregular one.
| Plain | Polite | |
|---|---|---|
| is expensive | 高い | 高いです |
| isn't expensive | 高くない | 高くないです |
| was expensive | 高かった | 高かったです |
| wasn't expensive | 高くなかった | 高くなかったです |
The first row is also the future: 明日も暑いです, "It will be hot tomorrow too."
What you'll say and hear
One adjective can be the whole sentence.
It's cold today, isn't it?
Thank you for the meal. It was delicious.
The adjective changes. です doesn't
After a noun you say でした for "was" and じゃない for "isn't". After an い-adjective you say neither: the adjective has already said it. In plain style it takes no だ either.
It was cold yesterday.
Not said: 昨日は
(It was cold yesterday.)
This bag isn't expensive.
Not said: このかばんは
(This bag isn't expensive.)
This bag is light.
Not said: このかばんは
(This bag is light.)
くないです or くありません?
Both are polite. くないです is the everyday one. くありません is more formal, and its past is くありませんでした.
This problem is not difficult.
Yesterday's meeting was not long.
Before a noun
Nothing goes in between: no の, no な.
I bought new shoes.
Do you have a bigger box?
Not said: 新しいの
(I bought new shoes.)
いい: よくない, よかった
Only いい and いいです keep the い. The rest come from よい, a more formal form of the same word, so there is no いくない or いかった. かっこいい (cool) has いい inside it and does the same: かっこよかった.
Yesterday's movie was good.
The weather is not good today.
よかった by itself says you are glad or relieved.
I found your wallet.
Oh, thank goodness.
Which kind is it?
Every い-adjective ends in い, so 静か and 便利 can't be one. The catch is a few な-adjectives that end in い as well. The three you meet first are きれい (pretty, clean), 嫌い (disliked) and 有名 (famous).
This room isn't spacious.
広い is an い-adjective: its ending changes.
This room isn't clean.
きれい is a な-adjective: it stays whole, and じゃない follows.
Not said: この
(This room isn't clean.)
Nor きれくない.
Close neighbours
A な-adjective never changes. だ or です after it does, and before a noun it takes な.
I study at a quiet library.
じゃないN4
In casual talk, じゃない after an い-adjective isn't "not". It means "it is, isn't it".
Hey, this cake is better than I expected.
Check yourself
1"Yesterday's test was easy."
昨日の
Choose an answer to see why.
2"The weather wasn't good."
天気が
Choose an answer to see why.
3You are talking to a friend. Which is right?
Choose an answer to see why.
More detail
大きな and 小さな
大きい and 小さい each have a second shape, used only before a noun, with the same meaning.
There is a large tree in the garden.
多い
"Many trees" is not 多い木. 多い normally comes after what there is a lot of.
This park has many trees.
More sentences
This room is bright.
It is not cold today.
It was hot yesterday.
Last week's exam was not difficult.
It was not very cold this morning.