7th grade, 3rd class in Engpsh can be referred to as "Seventh Grade, Third Class."
The source of this terminology comes from the education system in Engpsh-speaking countries, where students are divided into grades based on their age and academic level. Each grade is then further divided into classes, which are typically numbered.
Example sentences:
"I'm in 7th grade, 3rd class."
"John is my classmate in 7th grade, 3rd class."
Translations:
"我在7年级3班。"
"约翰是我7年级3班的同学。"