In the present tense, German verbs whose infinitive stem ends in -t equally:
add -est and not -st in the "du" form
add -et and not -t in the "er/sie/es" form
add -et and not -t in the "ihr" form
Verbs with a stem in ending in -t include:
A-E: achten (to respect), antworten (to answer), arbeiten (to work), auflisten (to list), ausbeuten (to exploit), ausbooten (to kick out), ausbreiten (to spread out), auskundschaften (to find out), ausmisten (to muck out), ausrotten (to eradicate), ausstatten (to equip), befristen (to limit), begleiten (to accompany), begutachten (to give expert advice about), behaupten (to assert), beichten (to confess), bekleiden (to dress, to clothe), belasten (to burden), belichten (to expose), beobachten (to observe), bereiten (to prepare), beten (to pray), bewerten (to evaluate), bewirten (to feed; to entertain), bitten (to ask), bluten (to bleed), brüsten (to boast), brüten (to brood), bürsten (to brush), dichten (to write, to compose), deuten (to point), duften (to smell), dünsten (to steam, to stew), entkräften (to weaken; to refute), sich erkälten (to catch a cold), ernten (to harvest), erröten (to blush)
F-M: falten (to fold), flirten (to flirt), flüchten (to flee), fürchten (to fear), gestalten (to shape), gestatten (to permit), gewährleisten (to guarantee), haften (to be legally responsible), härten (to harden), hasten (to hurry), heften (to pin, to fix), heiraten (to marry), horten (to hoard), husten (to cough), hüten (to look after), kneten (to knead), knoten (to knot), kosten (to cost), läuten (to ring), lauten (to be, to amount to), leisten (to achieve), leiten (to lead), leuchten (to shine), lüften (to air), mieten (to rent, to hire)
N-S: pachten (to lease), punkten (to score points), pusten (to puff, to blow), retten (to save), richten (to direct, to focus), rosten (to rust), rüsten (to arm), schalten (to switch), schlachten (to slaughter), schlichten (to mediate, to arbitrate), schmachten (to languish, to pine), schütten (to pour), sichten (to look through), spalten (to split), spotten (to mock), spurten (to spurt), starten (to start), stiften (to found, to donate)
T-Z: tasten (to feel, to grope), testen (to test), töten (to kill), trachten (to strive), trösten (to console), übernachten (to spend the night), veralten (to grow old), veranstalten (to organize), verarzten (to patch up), verbluten (to bleed to death), verbreiten (to spread), verdursten (to die of thirst), verhaften (to arrest), verkraften (to cope with), vermarkten (to market), vermuten (to assume), vernichten (to destroy), verpflichten (to oblige, to commit), verrichten (to perform, to carry out), sich verspäten (to be late), verunstalten (to disfigure, to scar), verwüsten (to devastate, to ravage), verzichten (to do without), vorbereiten (to prepare), warten (to wait), werten (to rate), wetten (to bet), wirtschaften (to economize), wüten (to rage), züchten (to breed).
These verbs with a stem in -t also include a number of verbs recently imported from English: babysitten (to baby-sit), chatten (to chat), jetten (to jet), layouten (to layout), sich outen (to out oneself), promoten (to promote), toasten (to toast).