Scientists have to work hard to keep _____ with modern discoveries and developments.
You could see the runners very well from ______ we stood.
All of the flowers now raised here have developed from those _____ in the forest.
The modern history of Italy dates from 1860, ______ the country became united.
We will be shown around the city: schools, museums, and some other places, _______ other visitors seldom go.
The old building, behind _______ was a famous church, was _______ we used to work.