Student or Learner
1. A: I heard Martha's gone back to school.
B: Yes, She's enrolled in night school to get a college degree.
2. Recently a Brazilian aeronautic company announced that it has
developed a single-engine ethanol-burning airplane.
In terms of tense agreement in grammar, I learned that if the tense of main clause is past, that of the other clause must be past(-ed) or the past perfect(had p.p). So, I think Martha's gone must be "had gone" or "went" in the sentence 1, and it "has developed" must be "had developed"
or " developed" in the sentence 2.
Could you explain that to me?