It is clear that the whole world is passing through a social revolution in which a central _____ must be taken by scientists and technologists.
10. Legend has ______ Sun Wu was buried here.
9.Not until the third day after the terrible earthquake ______ a phone call from his mother.
8.Without your kind help, we ______ in the experiment.
7.Since you are here, you ____ as well stay here for long.
6.What ______ great progress you have achieved in such ____ short time!