Period [.]
1. Use a period to show the end of a sentence.
Hockey is a popular sport in Canada.
The federal government is based in Ottawa.
2. Use a period after certain abbreviations.
B.C. is the province located on the West Coast.
Dr. Bethune was a Canadian who worked in China.
The company is located at 888 Bay St. in Toronto.
It is 4:00 p.m. in Halifax right now.
Question Mark [?]
Use a question mark at the end of a sentence to show a direct question.
How many provinces are there in Canada?
Note: do not use a question mark for indirect questions.
The teacher asked the class a question. Do not ask me why.
Exclamation Mark [!]
Use an exclamation mark at the end of a sentence to show surprise or excitement.
We won the Stanley Cup!
The forest is on fire!
Comma [,]
1. Use a comma to show a pause in a sentence.
Therefore, we should write a letter to the prime minister.
2. Use a comma with quotation marks to show what someone has said directly.
"I can come today," she said, "but not tomorrow."
3. Use commas for listing three or more different things.
Ontario, Quebec, and B.C. are the three biggest provinces.
4. Use commas around relative clauses that add extra information to a sentence.
Emily Carr, who was born in 1871, was a great painter.
Apostrophe [']
1. Use an apostrophe to show ownership of something.
This is David's computer.
These are the player's things. (things that belong to the player)
Note: For nouns in plural form, put the apostrophe at the end of the noun.
These are the players' things. (things that belong to the players)
2. Use an apostrophe to show letters that have been left out of a word.
I don't know how to fix it.

来源：金桥博客