Irregular Plurals

Irregular Plurals
Some words in English do not follow the regular patterns of making nouns plural. Normal plural formation is done by attaching -s or -es to the noun, e.g. boys, houses, cars, books, ladies.
However, some nouns form their plurals by changing one of the letters in the word. Some also change the sound of one of the letters. These words are mainly of foreign origins.
Singular. Plural
alga algae
syllabus syllabuses/syllabi
alumnus alumni
alumna alumnae
analysis analyses
axis axes
bacterium bacteria
oasis oases
phenomenon phenomena
stimulus stimuli
stratum strata
fungus funguses/fungi
focus. focuses or foci
appendix appendixes/ appendices

Rewrite the sentences below making the words in brackets plural.

  1. The novel described the (crisis) of the Gulf War.
  2. The book’s (index) was poorly arranged.
  3. Dr Yusuf placed some (memorandum) before the meeting
  4. Radio and newspapers are the mass (medium) of advertisement.
  5. The investigation by the police proceeded on wrong (hypothesis).