避免在php中的随机数组输出中重复

I'm currently working on a school project about php. The task is to design a website with some php navigation, a calculator, a truthsayer and some other functions. Now, I have a problem with the truthsayer I would like to get some help with. The truthsayer is a php randomizer that prints out a "truth" from an array I've set up. The truthsayer also prints out different amounts of truths depending on what number I give it. For example: If I type "3" into a box and presses enter, it will post three truths.I'm currently working on a school project about