. It is clear that the whole world is passing through a social revolution in which a central _____ must be taken by scientists and technologists.

Though lacking________, the young teacher manages the class very well.

The dog had such ________ to its master that it would not leave him, even when he  was dead．

The advice is of great ___ to our work.We all think it_____.

---- I’m sorry I stepped outside for a smoke. I was very tired. ---- There is no _____ for this while you are on duty.