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Principal parts of the verb Shake:

Present: He shakes. (third person singular - he,she or it)

Present Participle: Shaking

Past: Shook.

Past Participle: Shaken.

Explanation: In most cases principal parts of verbs forms, are derived from the root form, which is not conjugated. It does not have a prefix nor a suffix. It is accompanied by a "To" before the word. Therefore: To Shake. (the infinitive form)

When the root form of a verb form, forms the other principal parts of the verb, it is said to be a regular verb such as play and live.  

In the case of "To Shake", this is an irregular verb because not all the forms of conjugation follow the regular norm:

1.Present - adding (s) or (es) to the root word - in this case it follows the norm. Example: It shakes its fur.

2.Present Participle - adding (ing) to the root word. - in this case it follows the norm. Example: The dog is shaking its fur after a good bath.

3.Past - adding (ed) to the root word - does not follow the norm. - Shook.                                                                                         Example:  The dog shook its fur after the bath.

4.Past participle - adding (have, has and had + ed) to the root word- does not follow the norm. - Had shaken.                      Example: Before I could get hold of the dog's chain it had shaken its fur and splashed water on the visitors.