Complete the sentences with two of the words in brackets.

1.

Birds were the 1 for the first aeroplane designers. Early designs only flew for a few metres, but an 2 by the Wright brothers flew for twelve seconds in 1903.

(improved version /effective / inspiration)

2.

Microwave cookery was 3 4 when an engineer working with radar noticed that some chocolate in his pocket had melted during an experiment.

(discovered /innovation / by accident)

3.

An important 5 in transport history was the invention of the car in the 1880s. But horses were still 6 for transport until around the 1930s.

(coordinated / widely used / milestone)

4.

In the 1980s and 90s, lots of people 7 fax machines in their offices for communication. Millions of fax messages were 8 every day, but the arrival of the internet meant the end of fax technology.

(transmitted / installed / discovered)