Ответ:
В Past Participle у модального глагола can формы нет. Being able — выражение со значением «быть способным», а не форма причастия глагола can.
| Infinitive | Past Simple | Past Participle | Present Participle |
|---|---|---|---|
| begin | began | begun | beginning |
| can | could | — | — |
| find | found | found | finding |
| forget | forgot | forgotten | forgetting |
| strike | struck | struck | striking |
| think | thought | thought | thinking |
| understand | understood | understood | understanding |
| wear | wore | worn | wearing |
