### 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 are so low on intensity that the ball hits the rackets and is very vibrating, hard balls can't bear them and even a pro would have trouble handling them.

### 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.
