—I have worked hard at English, but it seems that I haven’t made any progress.—Keep on _____ at it, and you will be successful.
He can’t state clearly how long he has ___________ the bicycle?
This house is __________ for a family of five ___________.
---Why not stop __________ a rest?--- Oh, it’s so exciting that I can’t stop ____________ the model plane.
Don’t leave the tap ________ after washing hands.
The computer still works well, we _____ buy a new one at the moment.