Use the proper forms of the verbs. Mind the Sequence

Use the proper forms of the verbs. Mind the Sequence of Tenses rule.
1. The students were explained that the basic legal framework laid down in 1688 still (to remain), but its political content, and the political balance between its main elements, the Crown, the House of Lords and the House of Commons (to change) radically.
2. The teacher stressed that Oliver Cromwell (to create) a written constitution - The Instrument of Government - which (to be) effective only for a few years.
3. I read that constitutionalism (to be) part of the British political tradition at least since medieval times.
4. It is believed that the Magna Carta (1297) (to regard) as Britain's closest equivalent to a written constitution as it (to be) a source of inspiration for subsequent constitutional development both in the UK and overseas.
5. The teacher said that the ancient theory of separation of powers (to try) to combat tyranny by dividing the functions of government between groups with different interests so that no power centre (to act) without cooperation with others.
6. It was interesting to know that Australia, New Zealand and Canada each (to recognize) the Crown as their Head of State.
7. We were explained that since 1688 the functions and personal powers of the monarchy gradually (to reduce).
8. The report was devoted to the English Civil War (1642-1648) which (to be) the country's greatest internal conflict between supporters of Parliament and supporters of Charles I.
9. The reporter stated that three Parliaments (to summon) and (to dissolve) in the first four years of Charles I reign, then 11 years he (to rule) without one.
10. He informed us that since 1688 the unwritten constitution (to attempt) to adjust the economic and social changes within the broad principles which (to lay) down in 1688.
11. He stressed that the 1688 Glorious Revolution (to be) a compromise which (to design) to satisfy all the influential political and economic interests.
12. He tried to prove that the unwritten constitution (to have) the virtue of flexibility and (to permit) both evolutionary and constitutional changes.