请将下列句子译成中文。
23. This location is infinitely far from whatever charges are responsible for the electric field under study.
24. When applying these equations, whatever convention of signs for the Fs and X’s must be used consistently.
25. In 1895, a German physicist discovered what are now known as X rays.
26. The particular integral(2 )is obtained by an application of what is spoken of as the method of undetermined coefficients(待定系数法).
27. The integers(整数), the rational(有理的) numbers, and the irrational numbers constitute what we refer to as the real number system(实数系).
28. The presence of the iron in the coil has increased the magnetic induction(延感应) to over.500 times what it would be if the coil were in vacuum.