### Chinese: 它们强度很低，球打到拍子上面，振动非常大，硬球顶不住，高手都很难驾驭。
### English: They have very low strength, and when the ball hits the top of the racket, the vibration is very high, the hard ball can't be topped, and it is very difficult for the expert to manage.
### Errors: There is no error in the English translation.

### Improved English: They are low in strength, and there will be too much vibration when the ball hits on it; it cannot withstand hard balls, and even professional cannot handle it.
