One _____ of being able to speak English is that you will have more job opportunities.

You can’t park here, sir. It is ____ for the ambulances only. 

When he picked up a large sum of money by accident, he battled with his _____ whether he should keep it or return it to the owner.

We are at your service. Don’t ________ to turn to us if you have any further problems.

He promised to come but he didn’t _______until the meeting came to an end, which made me angry.