✨ 最佳解答 ✨
➀It is believed that he has made a fortune in his youth.
不正解。in his youthは過去のことで現在と繋がっていない(過去で完了している)ので、正しくはIt is believed that he (had) made a fortune in his youth.
➁He is believed that he made a fortune in his youth.
不正解。He is believed thatという構文はありません。
➂He is believed to have made a fortune in his youth.
正解。ここで使われているto have 過去分詞という構造は、一見すると現在完了形に見えますが、過去形の役割を果たします。➀で訂正した文(It is believed that he (had) made a fortune in his youth.)の主語をItからHeに変えると、➂の文章ができます。
➃He is said to make a fortune in his youth.
不正解。in his youthは過去の話なのに、to makeは近い未来の話なので、矛盾しています。