Book

1. Paper book

1.1. eyes feel comfortable

1.2. no need battery

1.3. we can read what we really need

2. Paper book

2.1. heavy

2.2. can't carry many books

2.3. ruined, tear off, etc

2.4. expensive

3. E-book

3.1. expensive: ipad, kindle, smart phone

3.2. eyes get tired

3.3. no battery? no books

3.4. download too many books

4. E-book

4.1. light

4.2. many books in one thing

4.3. cheaper than paper book