She is so credulous that she often falls for fake advertisements.

credulous 来自拉丁语词根 cred-（相信）加上形容词后缀 -ulous（倾向于...的），字面意思是"倾向于轻信的"。这个词形容一个人不加思考就轻易相信别人或事物，带有贬义色彩。