研究发现，一种名为CPEB的蛋白质与维持长期记忆有关，位于中枢神经系统突触上，这是大脑中连接神经的枢纽。记忆就被存储在这一约有1万亿个神经细胞和突触的复杂网络中。随着经历和知识的不断增多，新的枢纽形成，老的则不断加强。CPEB合成的蛋白质会随着记忆的形成加强突触，使突触可以长期保存这些记忆。
从上文可见，人的大脑能储存记忆的关键部位是______。
A．大脑中连接神经
B．1万亿个神经细胞
C．突触
D．CPEB合成的蛋白质
参考答案：C
解析： 原文说“记忆就被存储在这一约有1万亿个神经细胞和突触的复杂网络中。”“CPEB合成的蛋白质会随着记忆的形成加强突触，使突触可以长期保存这些记忆。”可见人的大脑能储存记忆的关键部位是“突触”。
| Children are a relatively modem invention. Until a few hundred years ago they look like adult, wearing grown-up clothes and grown-up expressions, performing grown-up tasks. Children did not exist because the family as we know it had not evolved. Children today not only exist; they have taken over in no place more than in America, and at no time more than now. It is always Kids Country here. Our civilization is child-centered, child-obsessed. A kid’s body is our physical ideal. In Kids Country we do not permit middle-aged. Thirty is promoted over 50, but 30 knows that soon his time to be overtaken will come. We are the first society in which parents expect to learn from their children. Such a topsy-turvy situation has come to abort at least in part because, unlike the rest of the world, ours is an immigrant society, and for immigrants the only hope is in the kids. In the Old Country, that is, Europe, hope was in the father, and how much wealth he could accumulate and pass along to his children. In the growth pattern of America and its ever- expanding frontier, the young man was ever advised to GO WEST; the father was ever inheriting from his son. Kids Country may be the inevitable result. Kids Country is not at all bad. America is the greatest country in the world to grow up in because it is Kids Country. We not only wear kids clothes and eat kids food; we dream kids dreams and make them come tree. It was, after all, a boys’ game to go to the moon. If in the old days children did not exist, it seems equally true today that adults, as a class, have begun to disappear, condemning all of us to remain boys and girls forever, jogging and doing push-ups against eternity. |
The sentence "In Kids Country we do not permit middle-aged" underlined in Paragraph 2 means that middle-aged ______ .
A．are not permitted to live in America
B．are not welcome in America
C．become old too quickly
D．have already been overtaken by children