1. ①
He(S) found(V) the puzzle(O) easy(C). = He(S1) found(V1) <that(接続詞) the puzzle(S2) was(V2) easy(C2)>(O1).
【参照】②彼は簡単なパズルを見つけた。③④彼は簡単にそのパズルを見つけた。
2. ②
Physical exercise [is thought](受動態) of as essential to your health. ※think of A as B AをBであると考える
= You(S) think of(V) physical exercise(O) as essential to your health. <能動態>
【参照】
①✕Physical exercise is thought to be as essential to your health. → 〇Physical exercise is thought to be essential to your health.
参考にしてください。