Study the following examples showing the use

A. 1. I've got two sisters. One of them is a nurse,... is still a student. 2. Only two of us are here.... students have already left. 3. Her two sons were playing in the garden. She turned her eyes from one to.... 4. There was... pause. 5. This hat is too small for me. Can you give me... one, a size bigger? 6. Alec whispered something from... side of the table. 7. Some people like spring,... prefer summer. 8. She went to the kitchen and came back with... cup of tea. 9. I've brought two of the books you gave me. I'll bring... books next Friday. 10. I'm not doing any English, I'm busy with... things now. 11. Three parachutes opened one after.... 12. He entered the room and saw Mike and Martha sitting on the sofa. He looked first at one, then at.... 13. He wanted to get to... side of the river. 14. I've lost my cigarette-lighter. I'll have to buy... one now. 15. Some people are lazy.... are energetic. Most people are a mixture of both. 16. Excuse me, waiter. Could you bring me... fork? I dropped mine on the floor. 17. Only two countries in South America, Bolivia and Paraguay, are inland. All of... have coastlines. 18. Wa­shington is one of the five states of the United States which borders on the Pacific Ocean. What are... states? 19. I'll

finish the report soon. Give me... twenty minutes and I'll be ready to go with you. 20. My sister has two children. One of them is five and... is seven. 21. Some people like to take vacation in the mountains,... prefer the seashore. 22. The Anderson twins are identical. They look alike, and they think alike. Sometimes when one begins a sentence,... finishes it. 23. Scandinavia consists of four countries. One is Den­mark,... are Finland, Norway and Sweden. 24. The car I bought last year turned out to be a real disaster! I'll never buy... one of the same make. 25. Some babies begin talking as early as six months;... babies don't speak until they are more than two years old. 26. Bob is no longer young. It's going to be difficult for him to find... job. 27. There are several means of mass communication. The newspaper is one. Television is....