单项选择题
A．moving some part of their body B．stopping what they are doing to listen C．directing the orchestra playing it D．wishing that they could conduct music properly
A．only human beings have problem-solving intelligence B．a person’ s memory is different from a computer’ s in every respect C．animals are able to solve only very simple problems D．animals solve problems by instincts rather than intelligence
A．Because it would be easier to put them together and carry them around. B．Because it would be lighter for people to carry them from place to place. C．Because people wanted to make it look nicer. D．Because people wanted to save the expensive metal they were made from.