Past Simple Tense VS Past perfect Tense

I had written articles on various topics before he (a)   (come)

He (a)   (read) different kinds of books before you came.

They (a)   football on that field before it started to rain. (play)

I came here after you (a)   (leave)

The poet (a)   (write) a romantic poem before he came to the program.

I (a)   (help) him to do the task after I had finished my work.

We (a)   (take) an ice-cream before we left the ice-cream parlor.

I couldn't get into the house. I (a)   (lose) my keys.

The plane had left by the time I (a)   (get) to the airport.

After the alarm had rung, he (a)   (wake) up.