我上一年级英语怎么说?

"上一年级" 在英语中可以说作 "last grade"。 "last" 意为 "最后的"，"grade" 意为 "年级"。

例如：

In my last grade, I had a hard time with math. (在我上一年级，我在数学上有困难。)
He did well in his last grade. (他在上一年级表现很好。)
She struggled in her last grade, but now she is doing much better. (她在上一年级有困难，但现在她做得更好了。)