前面的用介词in，例如：
1、The boy first showed promise as an athlete in grade school.这个男孩在上小学的时候就初次显示出成为运动员的潜力。
2、I was just in grade school at the time， but I remember it perfectly.那时我还在上小学，但是我记得非常清楚。
3、I'm John. I'm in Grade Eight at Rocky Mountain High School.我叫约翰，我在洛基山高中读八年级。
