Make mE a ます-stem master (Unit 5)
I know we're not worrying about mastering our conjugations just yet, but the earlier you learn how to put verbs into their ます-stem forms, the smoother your studies will be.
To form the ます-stem of a godan verb, we must change the final "-u" sound to an "-i" sound. Like this:
買う → 買い-（かう → かい-）
行く → 行き-（いく → いき-）
書く → 書き-（かく → かき-）
脱ぐ → 脱ぎ-（ぬぐ → ぬぎ-）
押す → 押し-（おす → おし-）
立つ → 立ち-（たつ → たち-）
死ぬ → 死に-（しぬ → しに-）
遊ぶ → 遊び-（あそぶ → あそび-）
飲む → 飲み-（のむ → のみ-）
座る → 座り-（すわる → すわり-）
As usual, we don't need to do anything to the stems of ichidan verbs:
食べる → 食べ-（たべる → たべ-）
寝る → 寝-（ねる → ね-）
Our Group III verbs change like this:
する → し-
来る → 来-（くる → き-）
Master all of the stem changes listed above, and you will be able to say a lot of things in Japanese. In our cheat sheet, we list only a few of them:
～ます is the polite present/future form:
～ません is the negative polite present/future form:
～ ましょう is the polite volitional form:
～なさい is the hierarchical command form (e.g. what a teacher uses when commanding students to do something; what a parent uses when commanding a child to do something; etc.):
Here are some sentences:
今日は早く寝ます。
きょう は はやく ねます。
I'm going to go to sleep early today (i.e. tonight).
Literally: “today + は + quickly / early + sleep.”
今日は寝ません！
きょう は ねません！
I'm not going to sleep today!
Literally: “today + は + will not sleep!”
今日は早く寝ましょう。
きょう は はやく ねましょう。
I think I'll go to sleep early today. // Let's go to sleep early today.
Literally: “today + は + quickly / early + let's sleep.”
早く寝なさい。
はやく ねなさい。
Hurry up and go to sleep.
Literally: “quickly / early + sleep (=[command]).”
毎朝パンを食べます。
まいあさ パン を たべます。
I eat bread every morning.
Literally: “every morning + bread + を + eat.”
パンは食べません。
パン は たべません。
I don't eat bread.
Literally: “bread + は + do not eat.”
パンを食べましょう。
パン を たべましょう。
I think I'll eat bread. // Let's eat bread.
Literally: “bread + を + let's eat.”
パンを食べなさい。
パン を たべなさい。
Eat the bread.
Literally: “bread + を + eat (=[command]).”
We can even take things a step further and attach some other verb endings that pair up with ます-stems.
ます-stem + ～たい = want to VERB
パン食べたい！
パン たべたい！
I want to eat bread!
Literally: “bread + want to eat!”
行きたい。
いきたい。
I want to go.
Literally: “want to go.”
ます-stem ＋ ～な = [casual suggestion]
食べな。
たべな。
Why don't eat (it)? // Eat (it).
Literally: "eat (=[casual suggestion])."
We can add よ to add a bit of emphasis:
行きなよ。
いきな よ。
Why don't you go? // Come on, just go.
Literally: "go (=[casual suggestion]) + よ."
Well, what do you think? Do I have you convinced that mastering ます-stems is worth your while?
I hope so. In any case, you'll see it so often that you'll master it naturally over time.