He doesn’t believe that what we told him is true. 他不相信我们告诉他的事是真的。

6.当宾语从句中含的否定为“not……at all”、“not a little”、“not a few”、“not enough”、“can’t help”等固定搭配时，否定不转移。如：
I think that he doesn’t know it at all. 我想他对那一点也不知道。
I suppose that it is not enough to remember the words if you want to learn the language well. 我认为如果你想把这门语言学好，那么只记单词是不够的。
I believe that you can’t help singing our national anthem when you win the first place in the Olympic Games. 我相信当你在奥运会上获得第一名时你会情不自禁地唱起国歌来。

7.当宾语从句中含“no”、“nothing”、“nobody”、“nowhere”、“hardly”、“seldom”、“little”、“few”等否定词或半否词时，否定不转移。如：
I believe that nothing can make me give it up. 我想任何事情也不能使我放弃。
I think that no one can escape if the ship sinks in the sea. 我认为如果这艘船沉入海底的话，那么谁也逃不掉。
I suppose that he is a man of few words. 我猜想他是一个言语不多的人。