单项选择题
A．people would pay more attention to the problem B．governments would take effective measures C．all sides concerned would make more efforts D．farmers would use less artificial fertilizers
A．he will use of only about 20 % of the brain's capacity B．the other 80% of his brain will grow in due time C．he had rather narrow forehead a few hundred years ago D．he will have to use his brain more and more as time goes on
A．is always B．hopes for a change C．never stops changing D．will live a different life