—We need to buy some summer clothes, John.—Oh, I never know ________when I'm in the store.
He devoted all the time _____ his research .
Mr. Liu dreamed ____ a big house for his parents after they retire.
On the bus I saw a student____ I thought was your brother.
We’ll never forget the days ______ we lived in the country.
He lives in a room _______ faces the south.