30．When you finish your work, don’t forget to put the tools back where they ________．

Over the past decades, sea ice _____ in the Arctic as a result of global warming.

 --- Do you think Mom and Dad   late?--- No, Swiss Air is usually on time.

The mother who lost her son insisted that the careless driver      for the traffic accident ___      yesterday .

—Got your driving license?—No. I ____ too busy to have enough practice, so I didn’t take the driving test last week.