英语语法There are cases （）speech has started late in a child who

英语语法
There are cases （）speech has started late in a child who eventually turns out to be of high IQ.(WHERE)
I'd like to find a job (where) i can combine my qualificatian with my interest .为什么不是which
we have to consider what to do in situations (where) there are many people .
Those successful deaf dancers think that dancing is an activity (where) sight matters more than hearing.
全部都选where的理由是什么,