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The planet Mars is the 【小题1】 and most similar planet to Earth. It is very interesting to 【小题2】. For example, Mars has seasons with 【小题3】 weather, but other planets have the same temperatures all year round. Was there life on Mars?   

To find out, scientists need to know if Mars ever had water. In 2004, two robot explores （探测器）, or “rovers”, called Spirit and Opportunity were 【小题4】 to look for signs of water. These rovers can drive over rocks and all kinds of rough ground. They can also use cameras and send 【小题5】 back to Earth. 【小题6】 of all, the two rovers found chemicals and patterns （图文） in the rocks that were probably made by water. Then, they moved to another area and found other rocks which may have been created by water. Now scientists think there was probably water on the planet long ago. Today they are still not sure if there was life on Mars. They 【小题7】 need more information to decide. The discoveries of the two rovers answered some old questions, but they also 【小题8】 many new ones.