单项选择题

Plateau's experiments were the first steps leading to the invention of ______.

A．eyeglasses
B．telescopes
C．bifocals
D．motion pictures
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单项选择题
A picture remains on the retina for ______.
A．6 seconds
B．second
C．16 seconds
D．1/6 of a second
单项选择题
The result of Plateau's first experiment was that ______.
A．he went permanently blind
B．he stopped staring into the sun
C．he went blind for a month
D．he found what he was looking for
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