Scientists have to work hard to keep _____ with modern discoveries and developments.
Students urged that the school library ______open during the long vacation.
As a new comer in the city, I’m dying for ______ that is near both my university and the downtown area.
She __________ have left school, for her bike is still here.
__________ many times, he finally understood it.
Every evening after dinner, if not ___________ from work, I will spend some time walking my dog.