题目

Rivers are one of our most important natural resources(资源). Many of the world’s great cities are located on rivers, and almost every country has at least one river running through it that plays an important part in the lives of its people.     Since the beginning of history, people have used rivers for transportation. The longest one in the United States is the Mississippi. The lifeline of Egypt is the Nile. To the people of India, the Ganges is great, but it is also important for transportation; ships can travel along it for a thousand miles. Other great rivers are the Congo in下列生殖方式不属于无性生殖的是A．种子繁殖 B．孢子生殖 C．出芽生殖 D．分裂生殖