It ____ Jack twenty minutes ____ the math problem yesterday.
When the post fell _______, Dennis Bass was appointed to fill it.
Many firms give away small quantities of their productions as _______ so that people can try them before buying.
The opening between walls was very narrow; it’s very hard for soldiers to _______ through.
A yellow taxi _______ alongside a truck at the traffic lights when an elderly woman was crossing the road.
—Our train to Shenzhen didn’t leave until 14:30 because of something wrong with the railway.—Such a long delay! This train at 13:00.