What if your smartphone or laptop starts charging as soon as you walk in the door? Scientists have developed a specially-built room that can conduct energy to a variety of electronic devices within it without plugs or batteries.

It’s a custom test room of about 18 cubic meters, built from conductive aluminum(铝) panels with a metal pole running down the middle. When the scientists ran an electric current through the walls and pole following a set pattern, it generated two separate magnetic (磁的) fields: one that fills the center of the room and the other that covers the corners, thus allowing any devices within the space to charge.

By carrying out tests, scientists found their method could deliver 50 watts of power throughout the room. firing up all devices they tested. Without safeguards, running currents through the room's metal walls would typically fill it with two types of waves: electric and magnetic. This presents a problem, because electric fields can produce heat in biological tissues and pose a danger to humans. So the team built capacitors, devices that store electric energy, in the walls. “It limits the safe magnetic fields to the room volume while limiting risky parts to all the components built in the walls.” lead author Takuya Sasatani explains.

The scientists also tested the room’s safety, and the result showed the absorption of energy would remain well below acceptable limits. “We’re not saying this technology is safe under all circumstances—we’re still exploring,” says study co-author Alanson Sample. “But it shows us that there's still much area to explore.”

But applying the technology is still far in the future. It’s just too burdensome to put aluminum sheets all over the walls-that benefit doesn't make sense yet. “We’ve just developed a brand-new technique. Now we have to figure out how to make it practical,” Sample says. Meanwhile, scientists hope to improve the efficiency of power conduction and remove spots that the charge does not reach.

【小题1】What does paragraph 2 mainly talk about?

A．What the room looks like.	B．How electric currents are generated.
C．How the special room works.	D．What the technology was developed for.

【小题2】What are the capacitors used to do?

A．Produce electric power.	B．Measure magnetic field.
C．Stop devices from heating.	D．Protect people from harm.

【小题3】What is Sample’s attitude to the technology?

A．Optimistic.

B．Cautious.

C．Doubtful.

D．Content.

【小题4】What’s a barrier to the technology's application?

A．The cost.

B．The safety.

C．The effectiveness.

D．The material.