材料一：

材料二：天子适诸侯曰巡狩，诸侯朝于天子曰述职……一不朝，则贬其爵；再不朝，则削其地；三不朝，则六师移之。

——《孟子·告子》

材料三：周平王东迁后，周王室的统治力大减，直接管辖的地区仅在洛邑一带。周天子虽然在名义上仍是天下“共主”，但已无力控制诸侯。

——人教版《中国历史》七年级上册

材料四：

请回答：

已知一次函数y=-x+b的图象经过第一、二、四象限，则b的值可以是(    ).

阅读下面材料，在空白处填入适当的内容（不多于3个单词）或括号内单词的正确形式。

    Not all memories are sweet. Some people spend all their lives trying to forget bad experiences.

    Now American researchers think they are close to developing a pill, ____ will help people forget bad memories. The pill is designed ____ (take) immediately after a frightening experience. They hope it might reduce, or ____ (possible) erase (抹去) the effect of painful memories.

    In November, experts tested a drug on people in the U.S. and France. The drug stops the body from ____ (release) chemicals that fix memories in the brain. So far, the research ____ (suggest) that only the emotional effects of memories may be reduced, not that memories are wiped out. They are not sure to the degree people's memories are affected.

    The research has caused a great deal of ____ (argue). Some think it is ____ bad idea, while others support it. Supporters say it could lead to pills which prevent or treat soldiers' troubling memories after war. They say that there are many people who suffer from terrible memories. ____, those who are____ the research say that maybe the pills can change people's memories and changing memories is very ____ (danger) because memories give us our identity.