As a surgeon, I cannot        any mistakes; it would be dangerous for the patient. 

.With everything arranged properly, the project is surely to _________ smoothly as planned, step by step.

Mammals ________ nearly all warm-blooded animals except birds.

—What are you doing,Mum?—I am______the carpet in order to get rid of the dust in it.

He ______ at once when I promised to help him.