I must say you really know how to paint.

I admire your ability to think on your feet.

You're great at swimming.

You can really skate.

Wow!

You tried really hard on that.

You have such a positive attitude.

You have really improved on ______.

What a creative solution to that problem!

You work very well with your classmates.

I love how you take ownership of that!

You did a good job.

We're so proud of you.

I'm very pleased with your work.

This is really a nice place.

You're looking great today.

Your smile is so contagious.

I really admire your hard work.

You have such a great sense of style.

Your Chinese is really surprising.

You’re very professional.

You’re so smart.

这些句子可以用来表扬同学在不同方面的能力，包括绘画技巧、思维方式、游泳技能、滑雪能力、努力程度、态度、细节处理、创意、团队合作、领导力等。希望这些句子能帮助你更好地表达对他人的赞赏。