Use the correct form of the word given in each sentence: 11. He and his ………… hung around shopping malls and city streets. (assist) 12. Why don’t you ………………… her for a drink at the club one evening? (invitation) 13. Brenda wanted to …………… her sympathy in a practical way. (demonstration) 14. Our city is the biggest …………… center in the country. (commerce) 15. He ………………….………………… completed his experiment. (success) 16. Who ………………….………………… the Internet?. (inventor) 17. We are ………… a survey of consumer attitudes towards organic food. (conduction) 18. The museum is staging an……………… of Picasso’s work. (exhibit) 19. They refused to give a reason for their………………………. (act) 20. I found his talk very………………….…………………. (interest)