English verbs have 5 principal parts with which other forms are derived using verb auxiliaries: base/stem, simple past/present, past participle, present participle and the infinitive (the “name” of the verb). Some also include the third person singular in the present tense as a principle part, as it is the only verb form that kept its inflectional ending in Modern English.
|Grammatical term||Symbol||Regular Verb||Irregular Verb|
|Infinitive||to + V1||to watch||to see|
|Base Form /
|Present Simple third person singular||V1+s||watches||sees|
|Past Simple /