单项选择题
A．the people disturbed from their eye-movement sleep B．the people showing no eye-movements C．the first group of people D．the people showing their eye-movements
A．a developing nation B．a developed nation C．every nation with a big population D．every nation with a small population
A．higher productivity, but a lower average income B．lower productivity, but a higher average income C．lower productivity, but a lower average income D．higher productivity, and a higher average income