What impressed me in Greece was that the oceans _______ the islands were deep blue and many cities lay on the bay.

Storm chasing is so dangerous that some chasers are often hurt in accidents ______ by driving in a heavy rain.

March 5 marks the 50th anniversary of the “learning from Lei Feng Day”, a day_____ in honor of the Chinese soldier Lei Feng.

They use computers to keep the traffic _____ smoothly. 

Standing on the platform, Professor Li kept silent for a moment,         on the audience below.