昆虫纲的主要形态特征是（）
A.虫体长管形，由头及若干形状相似的体节组成。头部有触角l对，体节除前3节外，每节有足2对
B.虫体分头、胸、腹三部，有触角l对，足3对，有翅或无翅
C.虫体分头胸部及腹部，或头胸腹融合为一体，有足4对，无触角，无翅
D.虫体分头胸部和腹部，有触角2对，步足5对，多数种类水生
E.虫体窄长，背腹扁，由头及若干形状相似的体节组成。头部有触角l对。体节除后2节外，每节有足1对。第1对足变形为毒爪
参考答案：B
Africans see many advantages by uniting the continent into a single nation, or by uniting several small nations of a particular region into a nation. In unity there is strength. Africans often point to the United States, formed by the original 13 states, as an example of this principle. Africa now is divided into many weak nations. United, they would be much stronger. Africans could then more easily deal with foreign efforts to control them. Also it would be easier to plan and carry out big projects like the building of highways and dams. The considerations for African unity go beyond the practical advantages it brings. As we have seen, one factor is that the feeling of belonging to a particular nation is not strong among Africans. If, for example, you were to ask a man from Paris " What are you?", he would certainly answer " A Frenchman". Ask the same question of a man from Ibadan in Nigeria and he might give one of three answers, or all three, depending on his education and outlook. He might say, " A Yoruba" (his people), or " A Nigerian," or just simply " An African." Another factor that enters into the desire for unity is that African leaders throughout the continent feel that they all have many things in common. They all lived through the experience of colonial rule. Many of them went to school and university with men who now lead other African countries. They all feel very angry about the way in which they were treated in the past. Compared with these strong bonds (结合)，which overshadow the borders of nations, the idea of building separate nations does not have so much meaning. Some leaders say they are ready, in fact, to give up their separate nations. Many nations have written into their constitutions(宪法), and they may give up their powers to a Pan-African government that will come into being.
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