乒乓球桌面是什么材质：

乒乓球桌面通常使用密度板材质，也称为高密度纤维板（HDF），这是一种由木质纤维和树脂制成的板材。这种材料非常坚固耐用，同时也具有很好的弹性和反弹性能，能够确保球的反弹效果和速度。此外，乒乓球桌面也需要进行特殊的涂层处理，以确保球的旋转和控制效果。

把一乒乓球压入盛有水：

您好！我可以用英文回答您的问题吗？如果您想要中文回答，也请告诉我。

Regarding your question, if you are asking what happens when a ping pong ball is submerged in water, then the answer is that the ball will float on the surface of the water. This is because the density of the ball is less than the density of water, so it is buoyant and will not sink.

If you have any further questions or if there is anything else I can help you with, please let me know!