单项选择题
A．they have all been shot B．they are too dangerous C．they are all hiding under the earth D．they could not get used to the cold weather
A．Because they had a device called kinetoscope. B．Because they asked Thomas Edison to help them. C．Because they got a way of using their own devices. D．Because Thomas Edison had successfully solved certain problems.
A．problems B．questions C．words D．phrases