1、It is said （that） he is only 13 years old.據(jù)說他才13歲。
2、.It is thought （that ）he is the greatest person in the world.他被認(rèn)為是世界上最偉大的人（同樣請(qǐng)寫出另兩種表達(dá)）。
3.It is known that 眾所周知......