classifiers are required before a nouns when referring to a specific noun such as "the cat", "this dog", or "those birds".
classifiers are also required when stating the number of a noun such as "a dog", "two trees", or "a few birds".
classifiers are not used when talking referring to the noun generally as in "I like dogs" or "Trees are good for the environment".
inanimate objects - ????
animals - dogs, cats, birds, etc.
stick-like objects - trees, plants, guns, canes, etc.
objects worn or moved by people - shirt, shoes, car, chair, etc.
globular objects - Earth, fruits, etc.
book-like objects - books, journals, etc.
thin objects made of paper - newspaper, paper, calendar
an event or an ongoing process - ???
people - man, woman, Vietnamese person, etc.
compositions - songs, drawings, poems, essays, etc.
buildings of authority - courts, halls, etc.