Examples of errors:
(1) I spended most of my boyhood there.
(2) When I saw her last she weared blue jeans.
(3) Something terrible must have happened to him.
(4) She didn't allowed me to eat it.
(5) It was better that I hadn't buy the car.
(6) They found communes.
(7) Ugly thoughts are often hid behind poetic language.
(8) Any love they might feel is shrinked to a minimum.
The rules of English verb morphology are extremely complicated, and-it is not necessary to formulate them here (cf. Quirk et al. 1972:§3.54-72). The principal parts (base form or stem, simple past, and past participle) of the verbs in the examples above are as follows: spend, spent, spent (cf. send, bend, lend, rend vs. mend, tend, blend, wend, contend, depend); wear, wore, worn (cf. bear. tear); happen, happened, happened (regular); found ('to establish', not to be confused with find), founded, founded (regular); allow, allowed, allowed (regular), buy, bought, bought (cf. bring, seek, think vs. cry, die, tie); shrink, shrank, shrunk/shrunken (cf. sink, stink vs. blink, link); hide, hid, hidden (cf. bite vs. side).