give the plural of these nouns
univercity  sky    party      way        leaf
thief          ski      key        tragedy  comedy
day            taxi    story      language    knife

Here are the correct plural forms of the nouns:

Rules for forming plurals

1. Consonant + y → ies: When a noun ends in a consonant followed by y, change y to ies. Examples: party → parties, sky → skies, story → stories.

2. Vowel + y → ys: When a noun ends in a vowel followed by y, simply add s. Examples: way → ways, key → keys, day → days.

3. Some nouns ending in f or fe → ves: Change f or fe to ves. Examples: leaf → leaves, thief → thieves, knife → knives.

4. Most other nouns → s: Simply add s. Examples: ski → skis, taxi → taxis, language → languages.

Note: The correct spelling is university, not univercity. Its plural is universities.