As there is less and less coal and oil, scientists are exploring new ways of making use  of ______________   energy, such as sunlight, wind and water for power and fuel.

The Summer Palace is really beautiful. In fact, I doubt whether China has _________ park.

Because of the strong sun Mrs. William’s new dining room curtains _____ from dark blue to gray within a year.

Here I can only give you some purely ___ views of how we can control the situation.

It is not socially          for parents to leave children unattended at that age.