Examples of three principal parts of verb?past tense
The five principal parts of a verb are: Infinitive, Present, Past, Present Participle, Past Participle.
The principal parts of a verb are the forms of the verb that you need to know in order to derive all the verb's possible forms. For "sing" these are:present tense: singpast tense: sangpast participle: sung
The principle parts cry are: is crying, cried, and has cried
sink sank sunk
Base form participle past past participle
"Seem" has a present indicative tense, generally considered the first principal part of a verb.
In the sentence, "Earlier, I helped the principal." the verb is "helped."