We went through a period_______ communications were very difficult in the countryside.
23. Everyone should remember it is very important to _____ the balance of nature toady.
22. She always ____ her opinion ____ facts.
21. Every morning, the fish mongers stood there ______ with the fishermen for fishes.
20. When Jack arrived, he learned Mary ____ for almost an hour.
19. They didn't _____ the wedding because of a heavy rain.