某同学在厨房中进行的活动，属于物理变化的是(    )

生物学的研究对象是（    ）

    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.