单项选择题

What does "smart" lighting system mean

A．It can be turned off when you don't speak, and be turned on when you speak.
B．It can adjust to the internal clock of human beings.
C．It can develop itself with time goes by.
D．It can respond to human beings' every demand.

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热门试题

单项选择题

Which of the following measures is NOT encouraged from the human health perspective

A．Offer plenty of natural light through windows and skylights.
B．Install bright blue LEDs near computer screens.
C．Offer plenty of electric lights in the room and close the wind to avoid bacteria.
D．Install "smart" lighting system.

单项选择题

In the following places, where can we not find the LEDs

A．Digital clock.
B．Traffic lights.
C．Swimming pools.
D．Cassette players' speakers.