1.Columbus discovered America five centuries ago, didn't he ? Did Columbus discover America five centuries ago? Did Columbus discover America or Mexico five centuries ago ? Who discovered America five centuries ago? When did Columbus discover America? 2.The Internet provides us with access to any library all over the world, doesn't it ? Does the Internet provide us with access to any library all over the world ? Does the Internet or the television provide us with access to any library all over the world ? What provides us with access to any library all over the world? 3.Not long ago people living in one part of the world didn't know much about the life of people in their neighbouring countries, did they? Did people living in one part of the world know much about the life of people in their neighbouring countries not long ago? Did people living in one part of the world know much or less about the life of people in their neighbouring countries not long ago? Who didn't know much about the life of people in their neighbouring countries not long ago ? What did people know about the life of people in their neighbouring countries not long ago? 4. These days anyone can read books on CDs, can't he ? Can anyone read books on CDs these days? Can anyone read books or magazines on CDs these days? Who can read books or magazines on CDs these days? What can anyone read on CDs these days?