已知﹣9，b₁，b₂，b₃，﹣1五个数成等比数列，则b₂=（　　）

Ice-cream is not good          our teeth, but it         good.      

In 1638, John Harvard donated some money and about four hundred books to a new university. This was the beginning of the library at Harvard University. The gift was so important that the university was named for John Harvard.
Thomas Bray began the first free lending library in the late 1600s. He set up more than 30 or these libraries in the American colonies. However, the idea for this kind of free library ended when Bray died in 1730. In 1731, Benjamin Franklin and some friends started the first subscription（订阅费） library in the United States. In a subscription library people pay money to become members, but they may borrow the books without paying again.
In the United States, every child had a free education. This idea soon led to free libraries. One of the first libraries that used tax money to buy books was a library in Peterborough, New Hampshire. This library was set up in 1833.