Want, can, have done
The frames for talking about yourself: what you want to do, what you want others to do, what you can do, and what you've done.
-tai
polite -tai desuwant to (do)
〜たい 〜たいです
Attaches to the verb stem for what you want to do (ikitai, tabetai) and conjugates like an i-adjective (ikitakunai, ikitakatta).
issho ni ikitai.
I want to go with you.
一緒に行きたい。
issho ni ikitai desu.
I'd like to go with you.
一緒に行きたいです。
For someone else's wants, quote them (ikitai tte) instead of stating them. Don't offer with -tai desu ka? (nomitai desu ka? sounds nosy); use -masen ka? or ikaga desu ka? instead. The object can take ga: mizu ga nomitai.
Learn alongside: -te hoshii, -tara ii na (Stage 3)
-te hoshii
polite -te hoshii desuwant someone to do
〜てほしい 〜てほしいです
Attaches to the -te form to say you want someone else to do something (kite hoshii, yamete hoshii), with the doer marked by ni.
issho ni itte hoshii.
I want you to come with me.
一緒に行ってほしい。
issho ni itte hoshii n desu kedo...
I was hoping you'd come with me...
一緒に行ってほしいんですけど…
Said straight at someone it presses: soften with n da kedo (casual) or n desu kedo (polite), and to ask a stranger or senior use -te moraemasu ka? instead.
Learn alongside: -tai, -tara ii na (Stage 3)Learn first: -te, hoshii, -tai
-eru / -rareru
polite -emasu / -raremasucan (do)
〜える／〜られる 〜えます／〜られます
Turns a verb into 'can': godan verbs change -u to -eru (iku -> ikeru), ichidan verbs swap -ru for -rareru (taberu -> taberareru), suru becomes dekiru; the object often takes ga (nihongo ga hanaseru).
ashita no paatii ikeru?
Can you make it to the party tomorrow?
明日のパーティー行ける？
ashita no paatii ni ikemasu ka?
Can you make it to the party tomorrow?
明日のパーティーに行けますか？
Casual speech drops ra in short verbs: mireru, koreru (ra-nuki); polite speech keeps -rareru. wakaru has no potential (wakareru = break up). mieru / kikoeru = it's visible / audible, vs mirareru / kikeru = get to see / listen.
Learn first: dekiru
-ta koto (ga) aru
polite -ta koto ga arimasuhave ever done
〜たこと（が）ある 〜たことがあります
Attaches to the past form to ask about or state experience (itta koto aru?, mita koto nai); casual speech drops ga.
okinawa itta koto aru?
Have you ever been to Okinawa?
沖縄行ったことある？
okinawa ni itta koto ga arimasu ka?
Have you ever been to Okinawa?
沖縄に行ったことがありますか？
With the plain present (iku koto ga aru) it means 'sometimes', not experience.