--Is your dad at home? --No, he_________ out.
. Getting to other planets or to the moon _____ many problems.
. In that country, the rich ______ richer, the poor, poorer.
. The project requires more labor than ______ because it is extremely difficult.
. Not one in one hundred children exposed to the disease ______ likely to develop it.
Robert is said ______ abroad,but l don't know what country he studied in.