Cathy______the knowledge of radio just by staying around the radio station.(唐山市)
I don' t know ____ to stay at home or go out.
The train leaves ____ 6: 00 p. m. So I have to be at the station ____ 5:40 p. m. at the latest.
____ he will come or not is still unknown.
We offered him our congratulations ____ his passing the college entrance exams.
He will come ____ you ask him.