Read the definitions carefully and select the correct words.
1. an arrangement or promise to do something, made by two or more people, companies, organizations etc
2. to try to do something, especially something difficult
3. engaged in war
4. having a strong desire to do something, so that you will not let anyone stop you
5. when people or groups fight each other in a war, in the street etc
6. become involved in a war
7. to have a meeting, party, election etc in a particular place or at a particular time
8. to have formal or official discussions about an issue or a situation
9. if an activity or situation involves something, that thing is part of it or a result of it
10. to take part in an activity or event, or be connected with it in some way
11. strong enough, well enough planned etc to continue for a very long time
12. a situation in which there is no war or fighting
13. to make an agreement
14. to refuse to accept, believe in, or agree with something
15. the act of not accepting, believing in, or agreeing with something
16. one of the people, groups, or countries opposing each other in a quarrel, war etc
17. formal discussions between governments, organizations etc
18. before a certain period of time has passed