例句與造句

1. In the mathematics of the nineteenth century, aspects of generalized function theory appeared, for example in the definition of the Green's function, in the Laplace transform, and in Riemann's theory of trigonometric series, which were not necessarily the Fourier series of an integrable function.
2. It's difficult to find theory of trigonometric series in a sentence. 用theory of trigonometric series造句挺難的