C. A newspaper

D. A book.

3. Why are physical libraries necessary to exist?

A. Everyone has a phone with them.

B. Some people are still used to the old ways.

C. More and more people use computers.

D. People can buy what they want there.

4.What does the text mainly talk about?

A. Libraries living on in digital age.

B. internet libraries nowadays.

C. Physical libraries in the past.

D. People's dream libraries.

Babbage, born in London in 1791, was a great mathematical genius. He was a natural inventor.

When he finished school, he went to study mathematics at Cambridge University. Later, he got a job teaching at the university. While working there, he designed his "first difference engine". This was, basically, a hand-operated mechanical calculator.

He took nine years to build a part of the machine. This machine can make complex mathematical calculations. It's a basic mechanical computer.

Babbage dreamed, however, of more complicated machines. In fact, he didn't only dream; he began to design them. The result was a series of "analytical engines" which were in fact powerful computers!

His designs contained processors, control units, a memory, and an input/output system. These are the four essential parts of a modern mathematical computer!

Alas! His "second difference engine" couldn't use electricity since this hadn't yet become a usable source of power, so Babbage had to make do with mechanical systems. For this reason, the machine was big, complicated and expensive. Though Babbage produced complete plans for the machine, he couldn't build it. It was too advanced for its age!

It was not until almost 160 years later that Babbage's "second difference engine" was finally manufactured. The first working version of this machine was built by the Science Museum in London, for the Babbage