His success _______ his hard work.
—He _____ to the meeting. Have you informed him of it? —Sorry. I _____ to.
It is not enough only_____the rules of grammar if you want to learn English well.
He _____the person referred to be put in prison.
_____you I owe a thousand apologies ____ having doubted your ability.
______at in this way, the present situation about birds flue doesn’t seem so disappointing.