be clever

My nephew is clever.

私のおいは利口です

My nephew is clever at school.

私のおいは学校で利口です

My nephew is clever at school even when he meets a hard problem.

私のおいは学校で難しい問題に出会っても利口です

My nephew is clever at school even when he meets a hard problem on his own.

私のおいは学校で難しい問題に出会っても一人で利口です

My nephew is clever at school, coming up with several approaches on his own even when he meets a hard problem.

私のおいは学校で難しい問題に出会っても一人でいくつもの方法を利口です