sweet spot
noun [ C ] uk/ˈswiːt ˌspɒt/ us/ˈswiːt ˌspɑːt/
（球拍、球棒等上的）最有效击打点
the part of a surface that is the best or most effective possible place to hit something
The new tennis rackets are lighter, stronger, and have a bigger sweet spot. 新网球拍更轻、更结实，而且有效击球区更大。