填空题.A. ability B. access C. admired D. allowed E. basically F. consuming G. current H. hiding I. includes J. motivation K. obvious L. passion M. premise N. value O. wisely The phrase bird-brain may be used to describe someone being silly, but this is not the case for ravens. Long 1 for their intelligence, ravens are now known to be able to plan ahead, a skill previously thought to belong only to humans. Researchers learned ravens could remember key information for a future task through tests. Until now, some corvids—the family of birds that 2 ravens—have shown the 3 to plan beyond the present, for example by 4 food for later. But the latest experiments revealed that ravens can 5 forego an immediate reward in order to get a better one in the future. In one of the tests, ravens were trained to use a tool to open a puzzle box in order to 6 a reward. And then, the ravens were presented with a tool to open a box and an immediate reward, but were only 7 to choose one or the other. Ravens remembered that the reward in the box was better than the immediate reward, and almost all of them chose the tool. Ravens' 8 for planning is still unknown, but it may be similar to ours. The human brain stores memories of past events to guide decision-making about 9 and future events. Planning tends to come about when the higher 10 of a future reward is palpable, or when one imagines the happiness that will come by retrieving food in the future.