English has many irregular verbs. In common use there are well over 200. Though these irregular verbs have many different forms, a number of them can be classified according to the forms of the past tense and the past participle. Here are eight different groups:
One group of verbs has a different vowel in the base, the past tense and the past participle. Verbs which belong to this group include begin, sing and swim:
1) begin-began-begun sing-sang-sung swim-swam-swum
Another group has the same form in the past tense and the past participle, but this form has a different vowel from that of the base. Examples of verbs in this category are bind, find and grind:
2) bind-bound-bound find-found-found grind-ground-ground
In this group of verbs the vowel stays the same but the ending changes in the past tense and the past participle. The word-final d of the base becomes a t. The verbs lend, send and spend belong to this category.
3) lend-lent-lent send-sent-sent spend-spent-spent
In the next group the vowel sound of the base changes in the past tense and past participle and a final t is added. Verbs in this category include feel, keep and weep.
4) feel-felt-felt keep-kept-kept weep-wept-wept
The following group of verbs have the same form in the past tense and the past participle, but this is different from the base. The vowel sound of the past tense and the past participle is /u/. The verbs fly, grow and know are in this category:
5) fly-flew-flew grow-grew-grew know-knew-knew
In the next group the vowel of the past tense and the past participle is different from the base, but it is not the vowel of the previous group. Verbs that belong to this category include hang, sit and win.
6) hang-hung-hung sit-sat-sat win-won-won
The next group of verbs has a vowel in the past tense and the past participle that differs from that of the base, and the past tense and the past participle have a word-final t. Examples of verbs in this category are buy, catch and teach.
7) buy-bought-bought catch-caught-caught teach-taught-taught
The final group of verbs has verbs that are the same in all forms. In other words, they are invariable. Verbs in this category include cut, hit and put.
8) cut-cut-cut hit-hit-hit put-put-put
English has many irregular verbs and these verbs have many different forms. In fact, this is true not only of English but of all Germanic languages. However, many verbs have the same patterns. As a result, the irregular verbs of English can be grouped into different categories.