to be occupied with sth · to have sth on one's mind · there is something the matter

No need to argue, there is nothing that only has bad effects and no benefits.

Were you able to do everything you wanted to get done?

Learn from the mistakes of others. You can never live long enough to make them all yourself.

I regret that I will be unable to meet you on February 27 owing to an unexpected matter.

Tom couldn't tell Mary everything he knew.