Tim, a third-grader, had difficulty with his schoolwork, and also found it hard to make friends.蒂姆是一名三年级学生，学习上有困难，而且交朋友也有问题。The most noticeable change was in my younger brother, who had grown quite a bit and was now a third-grader.变化最明显的是我弟弟，他长高了很多，已经是三年级的学生了。