Practice for 11/13 and 11/20 你还没考试吗？我以为你是昨天考试的。 我睡了八(个)小时，但是我还是很累。 他在玩游戏的时候见到很多人。
You still haven’t taken the exam? I thought you took the exam yesterday. I slept
for eight hours, but I am still tired. He meets a lot of people when he plays video games. Thanks!
the second is more natural if it is 我以为你昨天(参加)考试了。试 can be omitted sometimes, especially you have mentioned it before.
you can also use 碰到 or 看到 in the last.