The apostrophe (" ' ") has a variety of uses for conveying the concept of possession. Be aware of the difference in using an apostrophe with singular or plural nouns. A singular noun will use the apostrophe before the "s" ('s), whereas the plural version of that noun will use the apostrophe after the "s" (s'). This use comes with several stipulations discussed below.  Be mindful of nouns that are always considered to be plural, such as children and people. Here you should use 's even though the nouns are plural. Also be aware of pronouns that are already possessive and do not require apostrophes, such as hers and its. (It's means it is or it has). Their is possessive without apostrophe or s, except as a predicate adjective, where it becomes theirs. Here is an example of an apostrophe used to show possession with a singular noun:The hamster's water tube needs to be refilled.  Here is an example of an apostrophe used for showing possession with a plural noun:In the pet store, the hamsters' bedding needed to be changed.  Here is an example of an apostrophe used for showing possession with a plural noun that doesn't end with "s":These children's test scores are the highest in the nation. Contractions are shortened combinations of two words. For example, cannot becomes can't, "it is" becomes "it's", you are becomes you're, and "they have" becomes they've. In every contraction, the apostrophe replaces the letters that are omitted from one or both words.  Be sure to use the possessive pronoun your and the contraction you're appropriately. It is a common mistake to interchange them. Here is an example of apostrophes used for a contraction of it is and a singular noun with possession, while correctly being omitted for possessive pronouns (hers, theirs, its):Friends of hers explained that it's her idea, not theirs, to refill the hamster's water tube and change its bedding. Single quotation marks, which look almost identical to apostrophes, are used to separate quotations from other quotations which surround them. Use...

TL;DR in Vietnamese:
Sử dụng dấu nháy đơn cùng với chữ s để chỉ sự sở hữu. Sử dụng dấu nháy đơn để kết hợp hai từ tạo thành từ rút gọn. Sử dụng dấu trích dẫn đơn bên trong một trích dẫn thông thường để mô tả trích dẫn bên trong trích dẫn. Không được sử dụng dấu nháy đơn với s để biến danh từ số ít thành số nhiều.