英语中有一种主动句可以转换成两种被动句型，它们通常是一些表示客观说明的句子，如：
People believed that she is honest. 大家相信她是诚实的。
→ It’s believed that she is honest. 大家相信她是诚实的。
→ She is believed to be honest. 大家相信她是诚实的。
比较上面两类被动句型可以发现，一类是“it+be+过去分词+that从句”，另一类则是“主语+be+过去分词+不定式”(其中的“主语”为前一类句型中that从句中的主语)，通常可用于这两类被动句型的动词有assume, believe, expect, fear, feel, know, presume, report, say, suppose, think, understand等，比较(同时注意其中时态和动词形式的变化)：
It’s expected that he will come soon. / He is expected to come soon. 预计他很快就会来。
It’s expected that he has come. / He is expected to have come. 估计他会已经来了。
It’s known that is a good singer. / He is known to be a good singer. 大家知道他是位优秀的歌手。
It’s known that was a good singer. / He is known to have been a good singer. 大家知道他曾是位优秀的歌手。