This old book has severe bookworm damage, making it difficult to read.

This problem is very difficult.

This old book is a keepsake from my grandfather.

He suffered a big loss in his investment.

We suffered a great loss due to his irresponsible behavior.

There are various bugs in the garden.

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.