题目

US researchers have found traces of an ancient lake on Mars recently, increasing hopes of discovering evidence that billions of years ago the Red planet hosted life. The lake, which dates back some 3.4 billion years, appears to have covered as much as 80 square miles and was up to 1,500 feet deep, said the team from the University of Colorado. This is the first clear evidence of shorelines on the surface of Mars, said Boulder's research associate, Gaetano Di Achille, in a study published in the latest edition of Geophysical Research Letters. The identification of the shorelines and acc已知f（x）是奇函数，g（x）是偶函数，且f（x）-g（x）=1x+1，求f（x）= ，g（x）= ．