1. Mount Vesuvius hasn’t erupted for many years. (erupted, eruption)
2. What supplies shall we need for our mountain climb? (supplies, supplied)
3. He has got a powerful position in the government. (powerful, power)
4. He whistled happily as he rode along on his bike. (whistles, whistled)
5. The nurse was busy calming the frightened child. (calm, calming)
6. The students are sweeping the floor of the classroom. (swept, sweeping)
7. In all our travelling, we never saw an adult strike a child. (strike, struck)
8. The strike caused a great delay in the delivery of the mail. (delivery, deliver)
9. The medicine is an effective cure for a headache. (effective, effect)
10. The length of time we were there was two hours. (long, length)