题目内容：

For computer users, there is no bigger excitement than tossing out your old PC and upgrading to a newer, faster and cleaner machine. With hardware designers like Intel, pushing newer, faster products every year, and new software requiring even more powerful machines, companies and consumers have little choice but to go along.

But this rapid turnover is having a serious effect on the planet. Producing a personal computer consumes large quantities of natural resources. A recent study by the United Nations estimates the energy required to produce a single new computer is equivalent to nearly two barrels of oil. And that doesn't include the 22 kg of chemicals or the 1,500 kg of water used in the manufacturing process.

  In fact, pound for pound（均等地）, the process for making a car is about 500% more efficient than that for making a computer. That doesn't matter so much 20 years ago when personal computers were few and far between, but times have changed. These days, computers are found nearly everywhere and sales continue to grow. The number of PCs in use topped one billion in 2002.

Waste in production is only half the problem. Old computers, especially the monitors, are full of dangerous substances, which need to be carefully recycled. The problem is sure to expand over the coming years as users replace their boxy CRT monitors with LCD flat displays.

  Europe now requires that 70% of parts from old computers be recycled, but the study’s authors say that’s also part of the problem. The solution, they insist, is for governments and companies to encourage people to use their computers longer, and upgrade rather than replace. But considering that much of the world’s recent economic growth has come from spending on computers and information technology, that advice may sound like wishful thinking. 

1.What do computer users have to do every few years according to the passage?

   A. Push newer, faster products.

   B. Produce more powerful machines.

   C. Consume large quantities of natural resources.

   D. Upgrade to a newer, faster computer.

2.What does the underlined word “that” in paragraph 3 refer to?

A. The pound.                                   B. The process.

    C. The car.                                     D. The computer.

3.We can infer from the last paragraph that ____.

A. governments and companies will surely encourage people to use their computers longer

B. governments and companies will probably encourage people to replace their personal computers

C. the world's economic has been growing without people's spending on computers and information technology

D. all parts from old computers are now recycled in Europe

4.The purpose of writing this passage is ____

A. to encourage companies to push newer, faster personal computers

B. to encourage people to design more new software

C. to encourage people to save their personal computers

D. to encourage people to spend more money on computers and information technology