The plural of the study is studies. Dormitory is a dormitory. A knife is a knife.
The plural of dish is dish. Complex number of half dishes.half
Americans as adjectives: Americans; Americans; As a noun: American; Americans. The plural is American.
When used as a noun, it means "American", which can be singular or plural.
But when used as an adjective to mean "American", there is no singular or plural.
However, it should be noted that Chinese and Japanese are not singular and plural when used as nouns.
Rules for changing singular to plural:
1) 1. singular nouns plus s
2. if it ends with s, x, sh and ch, then add es.
3. "ending with consonant +y", y becomes I, and then es is added.
4. Nouns ending in O, except a few living "two people and two things" Negro, hero, tomato, potato and so on, usually add S directly after them.
2) The irregular change of nouns from singular to plural should pay attention to the following points:
1. Nouns containing man are generally changed from man to men. For example, women → women, police → police, British → British men. But Germans → Germans.
2. There are feet → feet, teeth → teeth, geese → geeks, etc. Change oo to ee.
3. Plural numbers ending in en include child→children, ox→ bull, etc.
4. There are mice → mice, uz → lice, etc.
5. Sheep, deer, fish, means, works (factories), Swiss, Japanese, China, etc.