单项选择题

One problem that has not yet been solved, it seems, is that ______.

A．a prototype has not yet been accepted
B．financial backing is not available
C．the machine will need fire-resistant sensors
D．the machine would not work if the ventilation was overwhelmed

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热门试题

单项选择题

According to the passage, because temperatures in a tunnel can be very high, ______.

A．the Robogat has to have a heat-resistant skin
B．the Robogat is operated in a control centre outside the tunnel
C．the Robogat can only work at the scene of a fire for a limited period
D．a Robogat is stationed at each end

单项选择题

When fire breaks out in a tunnel, the most important thing is to ______.

A．install a Rogogat quickly
B．detect the smoke quickly
C．change the ventilation
D．take quick actions