In Game Maker how do you make something happen by pressing two keys at the same time?

In GameMaker, you can detect simultaneous key presses by checking the state of both keys in the Step event. Use the keyboard_check() function for each key you want to monitor. For example, you can check if both keys are pressed using a conditional statement like if (keyboard_check(vk_left) && keyboard_check(vk_space)) { /* action */ }. This way, the specified action will only execute when both keys are pressed at the same time.