Here are the verbs in the correct tense, active or passive:

Nylon – The first man-made fiber

Nylon **was invented** (1) in the early 1930s by an American chemist, Julian Hill. Other scientists **were working** (2) with his invention and finally on 27 October 1938, Nylon **was introduced** (3) to the world. It was cheap and strong and immediately **became** (4) successful, especially in making of ladies' stockings. During the Second World War, the best present for many women **was** (5) a pair of nylon stockings, but more importantly, it **was used** (6) to make parachutes and tires.

Today, nylon **is found** (7) in many things: carpets, ropes, seat belts, furniture, computer and even **spare** (8) parts for the human body. It **has played** (9) an important part in our lives for over 50 years. Next year about 36 million tons of it **will be manufactured** (10).