It is known to us __________ it was not until 1938 ________ the first colour TV programme began to be broadcast in the world.

_______,parents should spend as much time as they can________with their children,thus they can influence them on the value of life.

It was a matter of________ would take the position.

In his lecture, the professor referred to the belief, in contrast to all other countries, ______the elderly are wise, ______is particularly dominant in the Chinese culture．

Air is to us _____ water is to fish.