To keep a cat away from the Christmas tree, you can try using a few different methods. One option is to place a physical barrier around the tree, such as a baby gate or fence. You can also use a spray bottle filled with water to spritz the cat if it gets too close to the tree, as cats generally don't like the sensation of being sprayed with water. Additionally, you can try distracting the cat with toys or treats to redirect its attention away from the tree.