Ответ:

Вставки по смыслу:

  1. A — the only planet he was ever going to live on
  2. B — I didn’t know anything, really
  3. C — how to fly a plane
  4. D — “How do they know that?”
  5. E — seem to know almost everything

Лишняя часть: how scientists find things out.

Ответ: A–3, B–2, C–5, D–6, E–4; лишняя — 1.