The World Health Organization gave a warning to the public without any______when the virus of H1N1 hit Mexico in April, 2009.
He told the boys________________.
—Do remember to take this medicine three times a day with warm boiled water. —_____.
Internet shopping will really _____ when people believe that it is safe.
Some students found _____ hard to study English well .
I hear a number of workers in the factory _____ out of work and the number of them ______ quite large .