The plural form of "focus" is foci, or the English plural focuses.
Latin words in which the singular ends in -us are typically pluralized by dropping the -us and adding an "i".
Examples include "stimuli" for stimulus, and "rhombi" for "rhombus."
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Foci and focuses are both acceptable.
(When used as a verb, "focuses" is the only acceptable form for the third person singular.)
"Foci" is formed using the Latin rule for plurals. It may seem more erudite in written communication, but in spoken form (foe-sigh) most people will not recognize the word. "Focuses" is a bit more awkward because of the multiple "s" sounds, but the general population is more likely to recognize it. If you are doing professional or scholastic writing, you should refer to your organization's style manual for the preferred form.
Emphasis is the singular form. The plural is emphases.
emphasy plura is emphasises
emphases
Emphases.
Emphasides or Emphasissetes are accepted.
Emphasis is the singular form. The plural is emphases.
Emphasis is the singular form. The plural is emphases.
emphasy plura is emphasises
emphasy plura is emphasises
the word emphasis is already singular because when in foreign plural it is emphases
It is pronounced "oh-AY-sees" with the emphasis on the middle syllable.
emphases
Emphases.
Emphasides or Emphasissetes are accepted.
Streams. (Emphasis on the "S")
The verb form of emphasis is emphasize (British spelling is emphasise).
There is no plural form. Do and Do not are verbs