I rode roller-skates infor a very long time today. I rode roller-skates for a very long time today.

After a very long time, I rode roller-skates in a very long time today. After a very long time, I rode roller-skates today.

I think the last time I did this was when I was in second grade in elementary school. I think the last time I did this was when I was in second grade in elementary school.

"this" refers to the subject of the previous sentence (rollerskating)

I think the last time I did this was when I was in second grade in elementary school. I think the last time I did this was when I was in second grade in elementary school.

I went to the roller-skating rink with my friends and a teacher infrom class. I went to the roller-skating rink with my friends and a teacher from class.

Not so clear if you went with your class as a class trip or just with this singular teacher and friends

We arrived in there earlier than the opening time so we had to wait a little bit. We arrived there earlier than the opening time so we had to wait a little bit.

We arrived in there earlier than the opening time so we had to wait a little bit. We arrived there earlier than the opening time so we had to wait a little bit.

After we got the skates and put our feet on the floor, everyone struggled to get used to balancefind their bodyalance and go forward. After we got the skates and put our feet on the floor, everyone struggled to get used to find their balance and go forward.

That is the expression I would use

After we got the skates and put our feet on the floor, everyone struggled to get used to balance their body and go forward. After we got the skates and put our feet on the floor, everyone struggled to balance their body and go forward.

It took me a few minutes but I soon got used to it soon. It took me a few minutes but I soon got used to it.

I didn't expect this wouldto be fun but I really enjoyed it. I didn't expect this to be fun but I really enjoyed it.

I felt like I went back to my childhood and haung out with friends in a very childish way. I felt like I went back to my childhood and hung out with friends.

I think I forgot the fun of doing something physically because I sait on my chair for a long time and study every day. I think I forgot the fun of doing something physically because I sit on my chair for a long time and study every day.

I want to go to an ice skating rink with friends sometime soon. I want to go to an ice skating rink with friends sometime soon.