Collins Cobuild English Grammar (201 page)

spoil		spoiled, spoilt
wet		wetted, wet

R75
    Here is a list of verbs with two past forms:

bid		bid, bade
wake		waked, woke
weave		weaved, wove

Here is a list of verbs with two
-ed
participle forms:

bid		bid, bidden
mow		mowed, mown
prove		proved, proven
swell		swelled, swollen
wake		waked, woken
weave		weaved, woven

     In American English,
gotten
is usually used instead of
got
as the
-ed
participle of
get
. However, American English always uses
got
rather than
gotten
in two common constructions:
have got
(meaning
own
or
possess
), and
have got to
meaning
must
).

Have you got change for the parking meter?
You have got to start paying more attention to deadlines.

The past forms of these constructions in American English are never
had got
. Instead, they use the past form of
have
.

Did you have change for the parking meter?
She said I had to start paying more attention to deadlines.

Note that some verbs appear in both the above lists as they have a different past form and
-ed
participle form, each of which has more than one form.