it is said(过去分词） that...（that引导主语从句）
据说……
it is believed/thought/said that...人们相信/认为/说……
It is said that she lived to be over 100. 据说她活了100多岁。
来源：《牛津词典》
It is believed that greenhouse gases are the main cause of global warming.
人们相信温室气体是全球变暖的主因。
It is thought that a management buyout is one option.
管理权收购被认为是一个选择。
来源：《柯林斯英汉双解大词典》