It is necessary for children to exchange ideas with parents from time to time so that the generation gap between parents and children can be _________.

theory

With so much water being used in the bathroom,it is no  _____ that more   environmentally friendly technologies have come out to make better use of water resources.

Mary would never do anything that was not _________ of by her parents in order not to make them unhappy.

How about the two of us ____ a walk down the garden?