prefix -nga- conveys the idea that an action is still going on.
72/ The only frequently-occurring feature of verb prefixes that remains to be covered is the way certain class concords are used with no noun of that class to refer back to. This can be mystifying at first, but once learned it is highly useful. 73/ When the subject of a verb is an infinitive or a noun clause, it usually follows the verb, and when such a subject follows, the subject prefix is i- , as for the singular of the N class (par. 13, 17). This in some whys corresponds to one use of 'it' as the subject of certain English sentences.
74/ When the PA—class relative concord is used with no locative noun to refer back to, it usually refers to time and is translatable as 'when.' This may be true even with a subject noun like wakati 'time,' which is in the U-N class.
75/ When the VI—class concord is used with no VI-class noun to refer back to, it usually refers to the manner in which something was done. This may be true even when the VI-class word refers to a noun like jinsi 'manner,' which is in the N class.
76/ The concords of the MA class are sometimes used where the MA-class noun mambo 'matters' may be said to be understood in the context.
77/ But the Swahili verb has suffixes (or 'extensions') as well as prefixes, Students, teachers and textbook writers sometimes slight the extensions, for at least three reasons:
1. Extensions don't have to do with matters like time, affirmation and negation, or who is doing the action.
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