He is good at studying

[keannu]

If you want to praise a model student, which would be the best way among these?
1. He is good at studying.
2. He is good at study.

What about the opposite case?
1. He is poor at studying.
2. He is poor at study.

 

[tedmc]

I don't think those are natural.

He is a good/brilliant student.
He is good at his studies.

 

[keannu]

Then, is only 1 natural?
1. Even though I'm a good student, if I don't make an effort, I wouldn't be able to enter a good university.
2. Even though I'm good at studying,...

Do you say "He is a poor student or bad student" if his academic performance isn't good?

 

[tedmc]

He did not do well in his studies/exams. He has poor academic record.
I think calling someone "a poor/bad student" would be undiplomatic and hurts one's self-esteem.

 

[Tarheel]

Sentence one is natural. Sentence two is not.

We say a person is a poor student.