Yes, "giggling" can be a participle when it is used to describe an action or state of being, such as "the giggling child." It functions like an adjective in this context.
The past participle of the word "have" is "had."
The past participle of the word "do" is "done."
The past participle of the word "Find" is the word "Found."
The past participle of the word "pick" is "picked".
The past participle of the word "finish" is "finished."
It can be, when describing a noun. However, it is a verb form, the present participle of to giggle, and may also be a noun (gerund).
giggling has three syllables
The girls were giggling.Giggling, she handed me a note. The whole class started giggling.
two
giggling
No, the word old is an adjective, not a participle.
The past participle of the word "pick" is "picked".
No. The word "vast" is a straightforward adjective, not a participle.
The past participle of the word "Find" is the word "Found."
The past participle of the word "have" is "had."
No, the word store is not a participle. The present participle is storing. The past participle is stored.
The past participle of the word graduate is graduated