AFTER HAVE, USE THE PAST PARTICIPLE
Simple sentence
They had walk to the school.
We have see the show.
He has took the test.
Have + Past participle
They had walked to the school.
We have seen the show.
He has taken the test.
Note: please carefully if the verb is in past participle.
1.
2.
3.
4.
She should (have done) the work.
She should have did* the work.
My friend (has sung) in the choir.
My friend sung* in the choir.