Recently, I've been troubled by a severe feeling of residual urine.

He complained of a feeling of residual urine and went to the hospital.

Nowadays, he goes to the gym every day.

Don't you think his behavior has been strange lately?

He is having trouble solving math problems.

He seemed to be in trouble.

I thought his behavior was really cruel.

I think his behavior is unjust.

I think his actions are completely inhumane.

Aldehyde is a very important compound in organic chemistry.