Ever since the food safety accident, the company has carried out _______ checks on milk products to make sure that they are of high quality..
_____ all the inventions have in common is ______ they have succeeded.
The new machine,if _________ properly,will work at least ten years.
—What were you doing when the telephone rang? —I ______ away my books and ______ to bed.
I thought Jim would say something about his school report,but he ______ it.
We found______ impossible to finish the work on time.