 Different verb tenses have different tonal patterns.The tones of verbs are made more complicated by the fact that some verbs have a high tone on the first syllable of the root, while others do not, and also by the fact that the sequence HH generally becomes HL by a rule called Meeussen's rule.Thus "asóma" means 'he reads', but when the toneless prefix "a-" 'he/she' is replaced by the high-toned prefix "bá-" 'they', instead of "básóma" it becomes "básomá" 'they read'.