It’s already 10’clock. I wonder how it ____ that she was two hours late on such a short trip.
______, the library was closed.
Tom and Jack went ______ they could find work.
He wrote his first novel ______ studying in a university.
The doctor ______ she sent her friend is very famous.
The old lady ______ the girl ten Yuan for washing windows, most of ______ hadn't been cleaned for a long time.