20世纪以来的三大理论对中国社会发展产生了重大影响。根据提示。完成下列有关三大理论的探究任务。

(1)根据所学知识，写出下列知识结构中字母代表的历史意义。

(2)根据下列材料，简述三大理论间依次“继承”的主要表现。邓 * * 是怎样依据“实事求是”的原则解决台湾和香港问题的?

材料一 ……我们完成了孙先生没有完成的民主革命，并且把这个革命发展为社会主义革命。我们正在完成这个革命。

—毛 * * 《纪念孙中山先生(一九五六年十一月十二日)》

材料二：毛 * * 思想的基本点就是实事求是，就是把马列主义的普遍原理同中国革命的具体实践相结合。……毛 * * 同志所以伟大，能把中国革命引导到胜利，归根到底，就是靠这个。马克思、列宁从来没有说过农村包围城市，这个理论在当时世界上还是没有的。但是毛 * * 同志根据中国的具体条件指明了革命的具体道路，在军阀割据的时候，在敌人控制薄弱的地区，领导人民建立革命根据地，用农村包围城市，最后夺取了 * * 。……我们高举毛 * * 思想的旗帜，就要在每一时期，处理各种方针政策问题时，都坚持从实际出发。

——邓 * * 《高举毛 * * 思想旗帜，坚持实事求是的原则(一九七八年九月十六日)》

(3)20世纪以来的三大理论的发展历程，反映了思想领域发展的基本规律是什么?

When a disease of epidemic proportions threatens the public, scientists immediately get to work, trying to locate the source of affliction and find ways to combat. Vaccination is one of the effective ways to protect the (1) population of a region or country which may be (2) grave risk. The process of vaccination allows the patient’s body to (3) immunity to the virus or disease so that, if it is encountered, one can fight it (4) naturally. To accomplish this, a small weak or dead (5) of the disease is actually injected into the patient in a controlled environment, (6) his body’s immune system can learn to fight the invader (7) . Information (8) how to penetrate the disease’s defenses is (9) to all elements of the patient’s immune system in a process that occurs naturally, in which genetic information is passed from cell to cell. This makes sure that (10) the patient later come into contact with the real problem, his body is well equipped and trained to (11) with it, having already done so before.

There are, however, dangers (12) in the process. (13) , even the weakened version of the disease contained in the vaccine proves (14) much for the body to handle, resulting in the immune system (15) , and, therefore, the patient’s death. Such is the case of the smallpox vaccine, (16) to eradicate the smallpox epidemic that nearly (17) the whole Native American population and killed massive numbers of settlers. (18) 1 in 10,000 people who receive the vaccine (19) the smallpox disease from the vaccine itself and dies from it. Consequently, the process, which is truly a (20) , may indeed hide some hidden curses.

19（）

A.infects

B.affects

C.effects

D.contracts