Past Simple vs Past Perfect

The storm destroyed the sandcastle that we (a)   (build).

He (a)   (not / be) to Cape Town before 1997.

When she went out to play, she (a)   (do / already) her homework.

My brother ate all of the cake that our mum (a)   (make).

The doctor took off the plaster that he (a)   (put on) six weeks before.

The waiter brought a drink that I (a)   (not / order).

I could not remember the poem we (a)   (learn) the week before.

The children collected the chestnuts that (a)   (fall) from the tree.

(a)   (he / phone) Angie before he went to see her in London?

She (a)   (not / ride) a horse before that day.