Experiments of the kind ____ in both the U.S. and Europe well before the Second World Wall.
I saw Helen at the party last month. It _________ a year since we met last time.
We will do what we can to get the goods _________ on time.
That they would win had been predicted and _________.
Take care! Accidents _________ happen along this part of the road.
That was because the school bus was _________ by a thick fog.