The past participle of "complete" is "completed." It is used in perfect tenses and passive voice constructions, for example, "The project has been completed."
The past participle of "keep" is "kept." It is used in perfect tenses, such as "have kept" or "had kept."
Light is currently considered to be the fastest known particle(s) in existence. There are theoretical particles that can function well past the speed of light. One example of such theoretical particle is the Tachyon.
The past participle of "show" is "shown." It is used in perfect tenses, such as in the sentence "She has shown great talent." Another form, "showed," is the simple past tense.
The amount of time for one particle of the medium to make one complete vibration cycle is known as the period of the wave. It is the time it takes for a wave to repeat its motion.
Neutrons are the important particles of nuclear chain reactions
Past is : Beat (itself) Past Particle : Beaten
The past participle of 'break' is 'broken'. The simple past tense is 'broke'.
The simple past and past participle is had.
The past participle for shrink is shrunk.shrink / shrank / shrunk
"Encouraged" is the simple past and past participle of the verb "encourage".
The past participle of do is 'done'.
The past participle is burst.
The past participle is drawn.
Been
The past participle (and simple past) is loved.
infinitive: be past: was/were past participle: been
The past tense is took. The past participle is taken.