When you wave to a friend,you are using sign language.
当你向你朋友挥手时,你使用的是肢体语言.
When you smile at someone,you mean to be friendly.
当你向某人微笑时,你表达了一种善意.
When you put one finger in front of your mouth,you mean “Be quiet.”
当你把一根手指放在嘴唇上时,你的意思 是在说 "别出声“ ”保持安静“.