Do you know the fact

Do you know the fact ____ Doris has been trying to hide in her pursuit of success?
A.which B.what C.when D.why
The other day,my brother drove his car down the street at ____ I thought was a dangerous speed.
A.as B.which C.what D.that

1 B 你知道Doris在追求成功时想要隐藏的是什么吗?空格要填的就是“什么“-what 指代the fact
2 B at which speed