If you put a buzzard in a pen six to eight feet square and open at the top, the bird will be a prisoner, though it can fly. The reason is that a buzzard always begins a flight from the ground with a run of ten to twelve feet. Without space to run, as its habit, it will not even try to fly, but remain a prisoner for life in its small buzzard prison with no top.
The bat that flies around at night cannot take off from the ground. If it is placed on the ground all it can do is to walk slowly about helplessly and no doubt, painfully. If it reaches a higher place, it will be able to throw itself into the air. Then it takes off immediately. But on flat(平的）ground, it will never fly.
A bee dropped into a cup will be there until it dies, unless it is taken out. It never sees the means of escape at the top, but keeps trying to find some way out through the sides near the bottom. It will look for a way where none exists(存在), until it completely destroys itself.
In many ways, there are lots of people like the buzzard, the bat and the bee. They are struggling about with all their problems and difficulties, not realizing that the answer is right there above them.
B . 
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D . 
