---I’m not sure_____ Mr. Wang goes to see his parents ---Twice a week.A. how long B. how often C. how soon
—Can you play foot ball? —________.It’s hard.
In some Western countries shops are closed ________ weekends.
Our teacher always helps us ________ our English.
The desk is not dirty.You ________ clean it.
He is very good ________ the children.