Study the information how to form the past perfect.
subject + had + past participle
You had decided what to do by 5 o'clock yesterday.
subject + had + not + past participle
You had not decided what to do by 4 o'clock yesterday.
had + subject + past participle
Had you decided what to do by 6 o'clock?
Past participle
Irregular verbs
You have to know all the forms of the irregular verbs very well. For the past perfect you need the form of the verb which can be found in the 3rd column of the table of the irregular verbs
go – went – gone
Regular verbsadd -ed
work – worked
Sometimes there are exceptions in spelling when adding -ed:
Consonant after a short, stressed vowel at the end of the worddouble the consonant:
stop – stopped
swap – swapped
In British Englishdouble one -l at the end of the word:travel – travelled
One -e at the end of the word
leave out the -e; add -d:
love – loved
save – saved
Verbs ending in -y
verbs ending in 'y' preceded by a vowel (a, e, i, o, u); add -ed:play – played
change 'y' to 'i' after a consonant; then add -ed:worry – worried