人云亦云----echo one's words

例句:
A:It's said that she was born of a noble family and her mother used to be princess.
据说她出生于贵族家庭，而她母亲曾经是公主。
B:I don't believe it. Besides, don't echo other's words. You must prove it.
我不信。此外，不要人云亦云。你必须去证实它。

同义词：
pin one's faith upon another's sleeve
repeat like a parrot
say ditto