♡さんが現在使っている英文法参考書の『動詞の態』の中に、「注意すべき受動態の表現」(のような)のコーナーがあります。
They [say] that S … Sは…だと[言われている] の書き換え二つのパターン ※[say]:think/believe/know/report等も同じ
【例】They say that Kate is very considerate. ケイトはとても思いやりがあると言われている。※They:一般的な人々
① It is said that Kate is very considerate. ケイトはとても思いやりがあると言われている。
② Kate is said to be very considerate. ケイトはとても思いやりがあると言われている。
1) They are said to be good soccer players. = It is said that they are good soccer players.
2) It is believed that the moon goes around the Earth. = The moon is believed to go around the Earth.
3) All of Dr. Hawking's books are thought to be difficult, but interesting. = It is thought that all of Dr. Hawking's books are difficult, but interesting.
4) It is known that Seattle is a big city. = Seattle is known to be a big city.
参考にしてください。