Past Perfect vs Past Simple

I wanted to pay for my shopping when I ........... (see) that I ............... (leave) my wallet at home.

We ................ (go) to the party together after I ............... (make) dinner.

Brian ................. (want) to talk about the argument he ................ (have) with Lucy the day before.

I ................. (forget) that I ............ (post) that letter.

He ................ (visit) many other countries before he .......... (go) to Australia.

He ............. (go) before I .............. (can) speak to him.

He ............. (leave) after I ............... (speak) to him.

I didn't know you .................. (already/lend) her 100 dollars and I ................. (give) her another 50 dollars.

Before she ............... (go) to work, she ................ (feed) her cats.

My mother ............... (decide) to let the flat after she .............. (inherit) it.