词尾 -ed 有三种不同的发音。

/t/

若动词尾音为清辅音 (s, k, ch, sh, p, g, h)，则词尾应加 /t/ 音。
We worked all day.
He helped me.
She laughed at me. 

/d/

若动词尾音为浊辅音（如：b, g, v, z, m, n）或元音，则词尾应加 /d/ 音。

I cleaned the house. 
We arrived late.
They listened to music.

/Id/

若动词尾音为 /t/ 或 /d/，则应加 /Id/ 音作为额外的音节。
We wanted to see the fireworks.
We invited many people.
I decided to go out.