If you're unable to concentrate on a problem, your cognitive performance significantly decreases.

如果你不能集中精力解决一个问题，你的认知能力就会明显下降。

And so the student often feels lonely, unhappy, unmotivated and unable to concentrate on studying. Or there may be other things bothering you.

所以，学生经常感到孤单，不开心，没有动力，不能集中精力到学习上。或存在其他困扰。

But when there are many mistakes, you become unable to concentrate on them.

但是当有很多错误的时候，你就不能集中精力。