火星有四季？

New observations of mud cracks made by the Curiosity rover show that high-frequency， wet-dry cycling occurred in early Martian surface environments， indicating that the red planet may have once seen seasonal weather patterns or even flash floods.

“These exciting observations of mature mud cracks are allowing us to fill in some of the missing history of water on Mars. How did Mars go from a warm， wet planet to the cold， dry place we know today？ These mud cracks show us that transitional time， when liquid water was less abundant but still active on the Martian surface，” said Nina Lanza， the lead investigator of the ChemCam instrument onboard the Curiosity rover.

After years of exploring land， the rover entered a new area filled with sulfates（硫酸盐）， marking a major environment transition. In this new environment， the research team found a change in mud crack patterns， signifying a change in the way the surface would have dried. This indicates that water was still present on the surface of Mars occasionally; meaning water could have been present for a time， evaporated， and repeated until mud cracks formed. Additionally， the rover found evidence that the mud cracks were only a few centimeters deep， which could mean that wet-dry cycles were seasonal， or may have even occurred more quickly， such as in a flash flood.

These findings could mean that Mars once had an Earth-like wet climate， with seasonal or short-term flooding， and that Mars may have been able to support life at some point. “What’s important about this phenomenon is that it’s the perfect place for the formation of polymeric molecules required for life， including proteins， if the right organic molecules were present at this location，” another researcher said， “Wet periods bring molecules together while dry periods drive reactions to form polymers（聚合物）. When these processes occur repeatedly at the same location， the chance increases that more complex molecules formed there.”

（材料选自Science Daily网站，有删改）

1. What can we know from Nina Lanza’s words？

A. Mars had been a warm， wet planet.

B. The Martian surface has abundant liquid water.

C. Nina can show lead investigators the transitional time.

D. Nina has filled in the missing history of water on Mars.

2. What is the main idea of the third paragraph？

A. The formation of the rover.

B. The new finding of the researchers.

C. The exploration of the rover.

D. The new transition of the researchers.

3. What may be the consequence of Earth-like wet climate in Mar？

A. Flash flood. B. Protein’s variety.

C. Life formation. D. Molecules’ Complexity.

4. In which section of a website may this text appear？

A. Health. B. Science.

C. Education.    D. Entertainment.

1. A。（剩余407字）