Let's take a look at how to deal with your sentence endings. The three basic choices in end punctuation are the following:
|period||question mark||exclamation point|
Most of the time, a period will get the job done, but if you're asking a question or being emphatic about something, you'll probably need one of the other two. Read on for details.
Note: If an abbreviation that ends in a period is the last word in a sentence, no additional period is required.
WRONG: The preferred short form for Government of Canada is G.C.
REVISED: The preferred short form for Government of Canada is GC.
Note: Exclamation points lose their impact with overuse. Whenever possible, allow your words to create the emphasis, rather than relying on punctuation to get the point across.
For more information on end punctuation, see sections 7.03 to 7.12 of The Canadian Style.