用现代生物进化理论的观点解释细菌抗药性不断增强的原因是（ ）
A：使用抗菌素的剂量不断增大，病菌向抗药性能力增强方向变异
B：基因频率发生变化，抗性基因所占的比例越来越大
C：抗菌素对病菌进行自然选择，生存下来的病菌，其抗药性能力较强
D：病菌中原来就有抗药性强的个体，在使用抗菌素的过程中淘汰了抗药性弱的个体
What's the red star in the sky through a telescope(望远镜)? It is Mars. Do you want to know more about it? Take the “Mars Orbit Express”! “Mars Orbit Express” is a space probe (探测器). It was sent towards Mars by American scientists on August 12th, 2005. Its tasks are to study Mars' atmosphere and return photos to Earth. But before that “Mars Orbit Express” must travel about 100 hundred million kilometers and seven months. It reached Mars' orbit(轨道)in March, 2006. Mars and Earth have similar weight and size. However, Mars is closer to the sun than Earth. Mars is very cold. The average temperature is below 50℃. The temperature at noon only reaches 20℃ during a Mars day. Its atmosphere is mostly CO2. It has much sand and two moons---Phobos and Deimos. Scientists think Earth and Mars had similar beginnings 4.6 billion years ago. But while Earth supports millions of lives，Mars becomes bad. “Earth easily could have turned out like that.” said an scientist, “It is important for us to find out why and Mars Orbit Express' should do that.” “Mars Orbit Express” also would help scientists to learn what might happen to Earth in the future. “Mars Orbit Express” would work for about four years.
位于马来半岛和苏门答腊岛之间的海峡是（ ）
△ABC的两个顶点为A(-4,0)，B(4,0)，△ABC周长为18，则C点轨迹为( )
地壳的厚度约为8到40km，在地表以下不太深的地方，温度可按y=3.5x+t计算，其中x是深度，t是地球表面温度，y是所达深度的温度．
