____ have already sent ____ to ____ the surface of Mars, and ____ experiments to see if they can ____ any signs of life. So far, they haven't found any, but an ____ of rocks from Mars has ____ that they were created by the presence of water and wind. ____ life could have existed in the past.

Mars exploration

打印
嵌入

排行榜

视觉风格

选项

切换模板

恢复自动保存：？