It was a very hot day. A lion and a sheep were both thirsty (口渴的). The sheep found a small pool. Just when the sheep started to drink water from the pool, the lion came up to him and shouted, "I should drink first. I' m the king (大王) of all the animals. Get out of my way!"

    "No," said the sheep. "I should drink first. I found the water."

    "You will drink it all up," said the lion. "There won't be any left, and I' m almost dead (死的) with thirst.'

    "And I haven't drunk water all day," said the sheep.

    So they started to quarrel. They shouted louder and louder, and the lion even ran after the sheep to the top of a small hill.

    Suddenly the lion stopped. He looked up into the sky. The sheep looked up, too. A vulture (秃鹫) was there. All the animals knew and were afraid of him. He is Bird of Death, who likes to jump on the bodies of dead animals and eat them. The lion and the sheep knew it

    If we go on quarreling, said the lion, "we will both die of thirst, and the vulture will eat us. Go to the water and drink, but don't drink it all."

    The sheep did as the lion said, and the two animals weren't thirsty anymore.

       1967年              1973年            1995年             2004年

已知全集$U=R$，集合$A=\left\{x\right|x+1<0\}$，$B=\left\{x\right|x-3<0\}$，那么集合$\left(C_{U}A\right)\cap B=$（  ）

图中神经元a、b与痛觉传入有关，神经元c能释放脑啡肽，脑啡肽具有镇痛作用．请回答问题：