Periods are used at the end of sentences, with abbreviations, before decimals, and between dollars and cents. Question marks and exclamation points are used to end questions and sentences expressing strong emotion. Commas are used to separate introductory phrases from the main clause, in appositives, with independent clauses joined by conjunctions, and to separate items in a series.

1. PUNCTUATIO
N
MARKS

2. PERIODS

3. Rules for Using Periods

4. Use a period after an initial and after every part
of an abbreviation, unless the abbreviation has
become an acronym- an abbreviation that is
pronounced as a word, such as AIDS- or a widely
recognized name ( TV, NASA, PAGASA ). Titles
– Mr. Ms. Dr., and so on are also abbreviations
that take periods. If the abbreviation comes at the
end of a sentence, only one period is needed.

5. Examples:
•The tour leaves on Mon., Jan. 1,at 3 P.M.
•The book was written by J. O. Wells.
•The suspect was brought to the NBI.

6. Use a period before a decimal and between
dollars and cents, pesos and centavos.
Examples:
• A gallon equals 3.875 liters.
• The new textbook costs 39.50.
• The calendar costs P29.95.

7. Use a period at the end of a sentence that makes a
statement.
Examples:
• The oyster produces a pearl around sand or another
particle.
• The pearl formed inside the oyster.
• Pearls can be made into precious pieces of jewelry.

8. Use a period at the end of the statement that makes a
request, gives an instruction, or states of command.
Examples:
• Empty the kitchen trash before you take the garbage
out.
• Turn right at the first stop light, and then go to the
second house on the left.

9. Use a period at the end of a sentence that asks an indirect
question.
Examples:
• My neighbor asked if we had seen the cat.
[ The direct question was, “ Have you seen the cat?” ]
• Carrie wanted to know how we had arrived at the answer.
[ The direct question was, “How did you arrive at the
answer?” ]

10. QUESTION MARKS AND
EXCLAMATION POINTS

11. Rules for Using Question Marks and
Exclamation Points

12. Use question mark after a word or group of words
that asks a question even if it is not a complete
sentence.
Examples:
• What did you do last night?
• Will you put out the trash?

13. Use an exclamation point after a sentence
that expresses strong feeling.
Examples:
• Look out for that car!
• I just can’t stand the smell here!

14. Use an exclamation point after an interjection – a
word or phrase expressing strong feelings – when
it is written as a single sentence.
Examples:
• Ouch! You’re hurting me.
• Hurrah! We got four gold medals.

15. Use an exclamation point after a sentence
that begins with a question word but does not
ask a question.
Examples:
• How nice of you to do it for me!
• What a pleasant surprise that is!

16. COMMAS

17. Rules for Using Comma

18. Use a comma to set off introductory words,
phrases, and clauses from the main parts of the
sentence. The comma keeps a reader from
accidentally attaching the introductory portion to
the main part of the sentence and having to go
back and reveal the sentence.

19. Words
Examples:
•Disappointed, we left the movie before it
ended.
•Annoyed, the manager returned to his room.

20. Clauses
Examples:
•If we plan carefully for the grand opening, we
can increase sales.
•Because we left before the meeting ended, we
were not eligible to win a prize.

21. REMEMBER:
When the first part of the sentence is a subordinate or
independent clause, it is followed by a comma.
When the independent clause is the first clause in the
sentence, you would not need a comma.
Examples:
•When I received his e-mail, I replied at once.
•I replied at once when I received his e-mail.

22. Commas with Appositives
An appositive is a word or group of words that immediately
follows a noun or a pronoun. The appositive makes the noun or
pronoun clearer or more definite by explaining or identifying
it.
Examples:
o Rachel won the first prize, an expense-paid vacation to Hong
Kong.
o Nicanor Abelardo, a famous Filipino composer, was a native
of Bulacan.

23. Commas With Independent Clauses Joined By A
Conjunction
An independent clause is a group of words that could stand
alone as a complete sentence. A conjunction is a joining word :
and, but, or, for, nor, so, or yet. Sometimes a writer will
combine two or more independent clauses to form a compound
sentence. If a conjunction joins the clauses, places a comma
after the first clause.

24. Examples:
•I went to bed early last night, so I felt rested this
morning.
•The city’s economic situation has improved, but there
are still neighborhoods where many people depend on the
generosity of others in order to live.
•Susan worked through lunch, and now she is able to
leave the office early.

25. If the independent clauses are joined without a
conjunction, they are separated by a semicolon instead
of a comma.
Examples:
• I went to bed early last night; I felt rested this morning.
• Maria worked through lunch; now she is able to leave
the office early.

26. Commas to Separate Items in a Series
Commas are used to separate items in lists of similar words,
phrases, or clauses in order to make the material easier for the
reader to understand. The last item in a series is also usually
preceded by a conjunction. Use a comma before the final
conjunction to avoid confusion.
Examples:
•Al, Jane, John, and Mark all applied for the promotion.
•The instructions clearly showed how to assemble the
equipment, how to load the software, and how to boot the
system.

27. If each item in the series is separated by
a conjunction, no commas are needed.
Example:
• Ryan and Bryan and Ronron performed
at the company Christmas party.