The practice of hanging clothes across the street is a common ___ in many parts of the city.
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.