The Common Slavic rules governing the declension of nouns after numerals, which were described above, have been preserved in Slovene. In those Slavic languages that have lost the dual, the system has been simplified and changed in various ways, but many languages have kept traces of the dual in it. In general, Czech, Slovak, Polish and Ukrainian have extended the pattern of "three/four" to "two"; Russian, Belarusian and Serbo-Croatian have, on the contrary, extended the pattern of "two" to "three/four"; and Bulgarian and Macedonian have extended the pattern of "two" to all numerals. The resulting systems are as follows: