When people want to show they don't know or they have no idea,Englishman usually move their shoulders or with their palms up,Chinese people just shake their hand or head.For example,if someone want to signal a person to come here,as a British people,he or she would clench their fist and move the index finger back and forth,as a Chinese people ,he or she would move the fingers back and forth with the palm up.
In the expression did not know when or has no alternative, the English usually lets go and the peak peak shoulder, but the Chinese displays actually beckons with the hand or shakes the head.Also for example, when calls others come, English palm toMakes a fist swings with the index finger around, but Chinese palm to Finger curving swinging.