Please check my grammar. Thanks.
QUESTION:
Have I used the verb tenses in capital letters correctly, and are my sentences grammatical?
SENTENCES:
1. As you probably know, he's an old teacher. Suppose they [WERE] to fire old teachers tomorrow. If they [WERE NOT] to fire him, then by the end of this month it [WOULD BE] twenty years since he started teaching at that school. If they [WERE] to fire him, it [WOULDN'T BE].
2. As you probably know, he's an old teacher. If they [HADN'T MADE] the decision to fire old teachers, and if they [WERE NOT] to fire him tomorrow, then by the end of this month it [WOULD HAVE BEEN] twenty years since he started teaching at that school.