My classmates won't laugh at me if I don't do well in the exam. . . .

I can see that you are young and immature! To tell the truth, the decline in simulation results is not necessarily a joke, unless you are very unpopular in the class and despised by others! There's no need to care about this. Study is to give yourself a good future. What does it have to do with others? If you don't do well in the exam, others will walk away smiling. I don't care what I do, just be myself. The above is my personal experience. I hope they can help you and wish you progress in your study!