tones; the effect is such that even while the low tones remain at the lower end of the speaker's vocal range (which is itself descending due to downdrift), the high tones drop incrementally like steps in a stairway or terraced rice fields, until finally the tones merge and the system has to be reset. This effect is called tone terracing. Sometimes a tone may remain as the sole realization of a grammatical particle after the original consonant and vowel disappear, so it can only be heard by its effect on other tones. It may cause downstep, or it may combine with other tones to form contours. These are called floating tones. Tone sandhi In many contour-tone languages, one tone may affect the shape of an adjacent tone. The affected tone may become something new, a tone that only occurs in such situations, or it may be changed into a different existing tone. This is called tone sandhi. In Mandarin Chinese, for example, a dipping tone between two other tones is reduced to a simple low tone, which otherwise does not occur in Mandarin Chinese, whereas if two dipping tones occur in a row, the first becomes a rising tone, indistinguishable from other rising tones in the language. For example, the words 很 ('very') and 好 ('good') produce the phrase 很好 ('very good'). The two transcriptions may be conflated with reversed tone letters as . Right- and left-dominant sandhi Tone sandhi in Sinitic languages can be classified with a left-dominant or right-dominant system. In a language of the right-dominant system, the right-most syllable of a word retains its citation tone (i.e., the tone in its isolation form). All the other syllables of the word must take their sandhi form. Taiwanese Southern Min is known for its complex sandhi system. Example: 鹹kiam5 'salty'; 酸sng1 'sour'; 甜tinn1 'sweet'; 鹹酸甜kiam7 sng7 tinn1 'candied fruit'. In this example, only the last syllable remains unchanged. Subscripted numbers represent the changed tone. Tone change Tone change must be distinguished from tone sandhi. Tone sandhi is a compulsory change that occurs when certain tones are juxtaposed. Tone change, however, is a morphologically conditioned alternation and is used as an inflectional or a derivational strategy. Lien indicated that causative verbs in modern Southern Min are expressed with tonal alternation, and that tonal alternation may come from earlier affixes. Examples: 長 tng5 'long' vs. tng2 'grow'; 斷 tng7 'break' vs.