Excused from recycling （回收利用) because you live in a high rise with a rubbish chute （垃

Excused from recycling (回收利用) because you live in a high rise with a rubbish chute (垃圾道)？ You won't be for long. Miami's Mark Shantzis has made it simple for those living in tall buildings to use the chute and recycle too.

In Shantzi's Hi-Rise Recycling System, a chute leads to a pie-shaped container with six boxes that can turn a round when operated. The system, which fits in the same space as the chute and container now in use, enables glass, plastic, paper, and other rubbish to go into separate boxes.

The system is controlled from a board fixed next to the chute door. The board has a button for each class of recycling materials (as well as for unrecyclables). At the press of a button, a microcomputer locks all other floors' chute doors and sets the recycling container turning until the right box comes under the chute. The computer also counts the loads and gives a signal by phone when the box is full. And a particular piece of equipment breaks up the nonrecyclables.

Sorting(分类) recyclables before they are collected saves the use of expensive materials recovery equipment which otherwise has to do the sorting. Such equipment often makes materials very expensive, so expensive that tons of recyclables remain wasted. Shantzis believes his system could help recycled materials become more costeffective.

The purpose in writing this text is ______.

A．to encourage people to recycle their rubbish

B．to introduce a recycling system for high rises

C．to describe the use of computer technology in recycling

D．to explain the need for rubbish collection in high rises