Experiments of this kind ______in both the U. S. and Europe well before the Second World War.
______ all the texts that are written,stored, and sent electronically, a lot of them are still ending up op paper.
It rained nonstop for ten days , completely_____our holiday.
.—Without your help, we _____ this task on time.—My pleasure.
If he ___ that he ____ to work there, everything would be OK now.
.—You ____ have set aside more time to play with our kids.—I wish I ______, but you know how busy I was.