1Regrettably, the concert was cancelled due to the bad weather.
2Was the decision to postpone the project made regrettably, or was it a deliberate choice?
3The company has regrettably been forced to lay off several employees due to financial difficulties.
4Try not to be regrettably late for the meeting, as it will cause inconvenience to others.
5It is regrettably true that many people struggle to find employment in their chosen field after graduation.