_____ the city’s public school system should be open to the children of migrant workers has become the focus of discussion.
It is very common that former people have difficulty in _____ modern life.
I really don’t know ___ ___I kept the secret papers.
---Why do you look so upset? ---There are so many troublesome problems ____.
It didn’t _____ him that she would refuse his invitation
The seawater takes ____ a lot of heat in summer.