She will never forget her stay there __________ she found her son who had gone missing two years before.
They ___________ for two hours
Taiyuan,a city in North China,was struck by a heavy snowfall last week,________serious traffic problems.
It was not until the beginning of the twentieth century________to explore space.
A notice was________in order to remind the students of the changed lecture time.
It took________supplies to construct these energysaving houses. It took brain too.