You can only be sure of_________ you have at present; you cannot be sure of something _____ you might get in the future.
You will succeed in the end ____ you give up halfway.
Not until I began to work ________ how much time I had wasted.
Not a single song ________ at yesterday’s party.
I finally got the job I dreamed about. Never in all my life ________ so happy!
.Mary couldn’t make herself _______ attention to because her classmates made so much noise.