[4]
1) Brazil is (by far the largest country in) Latin America. ※by far+最上級(…) ずば抜けて…
2) Global warming is (one of the most serious problems) we face today.
3) (Nothing makes me happier than) letters from old friends.
4) John is as (good at shooting as any player) in the team. ※as ~ as any+単数名詞(…) どんな…にも劣らず~
5) Eri likes (looking after her dogs better than anything else).
[英訳]
1) Japan is one of the safest countries in the world.
2) I am not as good at sports as she. 私は彼女ほどスポーツが上手ではない。
3) Do you know which mountain is the second highest in the world?
4) In England roses are most beautiful in May. ※✕the most beautiful 他国のバラとの比較ではないのでtheを付けない
5) No other building in Yokohama is as tall as this one.
参考にしてください。