2026年5月托福机经套卷(第4套)Listen to an Academic Talk4 道题

Listen to an Academic Talk

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What is the talk mainly about?

ARecent advances in nanotechnology

BA problem with nanotechnology

CThe physics of nanotechnology

DVarious uses of nanotechnology

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正确答案：D

What advantage of a new sunscreen does the speaker mention?

AIt is invisible when applied on skin.

BIt can be used in any weather.

CIt does not contain titanium dioxide.

DIt is effective when used in tiny amounts.

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正确答案：A

What does the speaker point out about silver?

AIt was used in ointments for millennia.

BIt can stop the growth of harmful microbes.

CIt can help increase the transparency of glass.

DIt was considered more valuable than gold in ancient Rome.

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正确答案：B

Why does the speaker mention the amount of gold nanoparticles in pink tesserae?

ATo help explain why most of the tesserae were very expensive

BTo help people understand what ancient Roman tesserae looked like

CTo emphasize an effect of heating gold nanoparticles between layers of glass

DTo argue that the Romans knew how to use tiny particles for coloring tesserae

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正确答案：D