Past Perfect Tense

HAD + PAST PARTICIPLE FORM OF THE VERB

* for Regular verbs we add: d/ed/ - ied at the end:

arrive= arrived

wash=washed

study=studied

* for Irregular verbs the form changes completely:

go, went = gone

write, wrote= written

The bus had left by the time I arrived.

this means that the 1st action in the past was 'the bus had left' and then I arrived (the 2nd action in the past)

If you had studied harder, you would have passed your Math exam. OR:

this is an imaginary sentence about something in the past - it is a hypothesis and nothing can be done about it now.

I wish I had studied harder for my Match exam (but it's too late now)

If only he had arrived 10 minutes earlier, he wouldn't have missed the plane.

Direct Speech:' I forgot to send the email'

He told me that he had forgotten to send the email.

Direct Speech: 'I failed the Maths exam'

She said she had failed the Maths exam.

Use the Past Perfect!