Решение:
- England is separated from Scotland by mountains. (Present passive, как факт)
- It is washed by the North Sea. (Present passive, как факт)
- The main cities of England are situated in the centre of the country. (Present passive, как факт)
- London, its capital, was founded many centuries ago. (Past passive, так как указано время в прошлом)
Ответ: is separated; is washed; are situated; was founded.