C．researchers are developing new solar panels on roofs

D．the new material is a very thin sheet with many layers

19．How does the panel work?

A．It takes in the heat and cools it down. B．It uses a mirror to reflect the sunlight.

C．It sends heat away right into space. D．It has a window to let out the heat.

20．The new material is especially useful in areas that .

A．suffer high temperature B．have poor air conditioning

C．have plenty of food D．are short of power

21．What can you infer from the passage?

A．The appliance of the new panel is still under research.

B．Some people got benefits from producing the panels.

C．People may have problems in using the new material.

D．The new panels may save 15 percent of the energy.

　　 "Yes，I'll be ready at nine in the morning. Goodbye，dear，and thanks again." It had not been an easy telephone call for Mrs Robson to make. Her daughter had been very kind，of course，and had immediately agreed to pick her up and drive her to the station，but Mrs Robson hated to say that she needed help. Since her husband died ten years ago，she had been proud of herself on her independence. She had continued to live in their little house，alone.

　　That evening，however，she was standing at her livingroom window，staring out at the SOLD notice in the small front garden. Her feelings were mixed. Of course，she was sad at the thought of leaving the house，as it was full of so many memories. But at the same time she was looking forward to spending her last years near the sea，back in the little seaside town where she had been born and grew up. With the money from the sale of the house，she had bought a little flat there. She turned from the living room window，and looked round at the room. There was a small fish tank，with two goldfish in it. When asked why，her husband used to say，"It's nice to have something alive in the room." Since he had passed away，she had always kept some goldfish，and always had "something alive in the room"．

The next morning，as her train was pulling out of the station，Mrs Robson called to her daughter，"Kate，you won't forget to collect the goldfish，will you？The