If you apply for a patent for invention, can't others invent it?

As long as you can achieve unexpected results and make significant progress, you can apply for a patent. If it is really novel, creative and practical after examination, you can grant a patent right, and you can only use ~ ~ ~

Please note that for the combination formula of conventional products, some unexpected effects need to be achieved. For example, if you add salt to rice and you say that the effect is to make salty rice, then the effect is not unexpected and cannot be authorized, but if there is an effect that has not been discovered before, then it can be.