介词短语 for doing something作后置定语,表示目的,意思为用 于.的。 k algorithms received signals 大 Schemes these three functions have evolved, and shall describe the main ones. 次这里的ones是代词,避免重复。 x A working equation expresses the unknown quantity in terms of the known ones. x These equations are called differential equations, and now their study forms one of the most challenging branches of mathematics介词短语 for doing something 作后置定语，表示目的，意思为用 于的。 Schemes for performing these three functions have evolved, and shall describe the main ones. ＊ ＊ algorithms for decoding received signals ＊ 这里的 ones 是代词, 避免重复。 A working equation expresses the unknown quantity in terms of the known ones. ＊ These equations are called differential equations, and now their study forms one of the most challenging branches of mathematics. ＊