palatal, so that both zelené stromy 'green trees' and krásne stromy 'beautiful trees' feature the alveolar , rather than the alveolo-palatal . However, the adjective krásne (meaning 'beautifully') does feature the alveolo-palatal , resulting in a heterophonic homograph with krásne 'beautiful' (inflected), which features the same alveolar as the uninflected form krásny , which has an unambiguous spelling. There are some more examples of heterophonic homographs like this. The same difference can be found in Polish; 'beautifully' translates to pięknie , whereas the corresponding inflected form of 'beautiful' is piękne (with the same dental nasal as in the uninflected form piękny ). There, the difference is reflected in the orthography. When a voiced obstruent (b, d, ď, dz, dž, g, h, z, ž) is at the end of the word before a pause, it is pronounced as its voiceless counterpart (p, t, ť, c, č, k, ch, s, š, respectively). For example, pohyb is pronounced and prípad is pronounced . When "v" is at the end of the syllable, it is pronounced as labio-velar . For example, kov (metal), kravský (cow - adjective), but povstať (uprise), because the is morpheme-initial (po-vstať). The feminine singular instrumental suffix -ou is also pronounced , as if it were spelled -ov. Consonant clusters containing both voiced and voiceless elements are entirely voiced if the last consonant is voiced, or entirely voiceless if the last consonant is voiceless. For example, otázka is pronounced and vzchopiť sa is pronounced . This rule applies also over the word boundary. One example is as follows: prísť domov (to come home) and viac jahôd (more strawberries). The voiced counterpart of "ch" is , and the unvoiced counterpart of "h" is . One of the most important changes in Slovak orthography in the 20th century was in 1953 when s began to be written as z where pronounced in prefixes (e.g. smluva into zmluva as well as sväz into zväz ). The phonemic principle has been given priority over the etymological principle in this case. Rhythmical rule The rhythmical rule, also known as the rule of "rhythmical shortening", states that a long syllable (that is, a syllable containing á, é, í, ý, ó, ú, ŕ, ĺ, ia, , iu, ô) cannot be followed by another long one within the same word. If two long syllables were to occur next to each other, the second one is to be made short.