5. When _______about one of the biggest concerns today, many people mention the sharp rise in prices.
all day, I went to bed early.
There is a natural phenomenon scientists call the greenhouse effect.
Every time I returned after an , I felt stupid because I was behind the others.
However, the eruption itself is really exciting and I shall never forget my first sight of one.
I go back to sleep when suddenly my bedroom became as bright as day.