下列有关菌落的描述正确的是（ ） A．每个菌落都由大量不同种细菌组成 B．一个菌

Today’’s lecture we’’ll center on the prehistoric people of Nevada Desert. Now most of these prehistoric desert people (36)______the countryside throughout the year. You might think that they’’re wandering aimlessly. Far from it, they actually followed the (37)______of carefully planned moves. Where they moved depended on where food was (38)______. Places where plants were ripening or fish were (39)______. Now often when these people moved, they carried all their (40)______on their backs. But if the journey was long, extra food and tools were sometimes stored in caves or (41)______rocks. One of these caves is now an exciting (42)______ site. Beyond its small opening is a huge underground (43)______. Even though the cave is very large. It was certainly too dark and dusty for the travelers to (44)____________. But it was a great place to (45)____________. And tremendous amounts of food supplies and artifacts have been found there.The food includes dried fish, seeds and nuts. The artifacts include stone spear points and (46)____________. The spear points are actually rather small. Here is a picture of some that were found. You can see their size in relation to the hands holding them.

在全球化的过程中，下列对“全球城市”或“世界城市”的基本特点，叙述正确的是（）。

A.生产性服务业是知识密集型产业，因此，这些城市是知识创新的基地和市场

B.作为跨国公司的（全球性或区域性）总部的集中地，是全球或区域经济的管理／控制中心

C.都是国家的中心城市，对全球资本的运行具有强大的影响力

D.具有高度发达的生产性服务业（如房地产、法律、信息、广告和技术咨询等），以满足跨国公司的商务需求

E.城市是信息、通讯和交通设施的枢纽，以满足各种"资源流"在全球或区域网络中的时空配置，为经济中心提供强有力的技术支撑

将两个全等的不等边三角形拼成平行四边形，可拼成的不同的平行四边形的个数为（    ）．

如图所示，质量为60g的铜棒长为a=20cm，棒的两端与长为L=30cm的细软铜线相连，吊在磁感应强度B=0.5T、方向竖直向上的匀强磁场中.当棒中通过恒定电流I后，铜棒向上摆动，最大偏角θ=60°，g取10m／s²，求:

小题1:铜棒中电流I的大小.

小题2:铜棒在摆动过程中的最大速率.

（）会在创新过程中影响创新的结果。