Cross your fingers
Angela: "Good luck on your test tomorrow. We'll be crossing our fingers for you!"
Andy: "Thanks."
安吉拉：明天考试，祝你好运！我们为你祈祷！
安 迪：谢谢。
You cross your fingers when you try to make something happen by wishing that it will happen. A common saying: "Let's cross our fingers and hope for the best."
中文意思：交叉手指，祝你好运！
Word of mouth
Angela: "There has been talk at school about canceling the concert."
Andy: "Really? Who did you hear that from?"
Angela: "Just word of mouth."
安吉拉：听说学校要取消音乐会！
安 迪：真的吗？你听谁说的？
安吉拉：只是大家都这么传！
When you say that you heard something word of mouth, you are not being specific about whose mouth you heard it from; just that you heard it from another person.
中文意思：“口耳相传的”口碑。