The key answer of exercise 3

a)

1. dates back to
2. the outset
3. at regular intervals
4. was about to
5. for the foreseeable future / in years to come

b)

1. In years to come, we will remember this as a golden age.
2. Scientific breakthroughs don't happen at regular intervals; they occur irregularly.
3. AIDS probably dates back to the early 20th century, but began to spread rapidly in the 1980s.
4. We are about to enter an age of natural disasters.
5. From the outset, the internet was able to unite people around the world.
6. Poverty will be with us for the foreseeable future.