Mary, I________ John of his promise to help you.
I don’t think the experiment is ______ failure, because it has provided us with _____ valuable experience for our future tests.
____ you know your potential(潜力), you have to rely on many other people to get to where you are.
. It was not until Maggie had arrived at her office _____ her appointment with the doctor.
.When _____ my childhood, I get lost in happy memories of times now gone forever.
----- Now that you like the portable personal computer so much, why not buy one? It is of great use to your work. ---- Well, I can’t afford _____ computer at present.