0why? is cactus-cacti an exception?02br 02br 00it's easy to understand that:02br 02br 00bus-buses02br 00church-churches02br 00bush-bushes.....02br 00we add es after an s or ch or sh0-
0Cactus is from Latin and 01b00many but not all02b00 words that end in -us in Latin are made plural by changing -us to -i. However, most dictionaries will list the "English" as well as the Latin form of the plurals. Cactuses, octopuses. 02br 02br 00Virus must be one of the Latin words that does NOT take the -i ending. I thing I heard those words called