2PunctuationPunctuation in English writing is like traffic lights and traffic signs. It helps the reader understand what you are writing. The punctuation marks used most commonly in English are:Comma (,) Period (.)Semicolon (;) Question Mark (?)Colon (:) Exclamation point (!)Apostrophe (’) Quotation mark (“)
3The CommaUse a comma before a coordinating conjunction (and, but, or, nor, for, so, yet) when it is used to join independent clauses.She looks very young, but she is already in her 30's.If the two independent clauses are short and not likely to be misread, no comma is needed.The plane took off and we were on our way.
4Use a comma after an introductory clause or phrase. When Sam looked in the path near the school building, he found his lost book.When Mary was ready to eat, her cat jumped onto the table.
5Use a comma after an introductory participial phrase that describes the noun or pronoun that follows.Struggling with large amounts of homework, the class feared the exam.Having seen pictures of the beach, the children eagerly looked forward to summer.
6Exercise 1.1: add or delete commas As the concert began we heard a tremendous explosion.With their local knowledge and low population density the people can fulfill their daily living needs by using the natural resources around them.Further the steep topography makes most of the land very susceptible to erosion.Beyond these flat riverside areas low nutrients shallow soil poor drainage and high rainfall limit the development of large plantations.
7Use a comma between all items in a series. I brought my books, papers, and computer to the classroom.We will prepare the specimens, conduct the tests, and record the data.
8Use a comma between coordinate adjectives not joined with and. Same has become a strong, confident, independent man.The laboratory is a small, windowless, poorly lighted room.The laboratory is a windowless, poorly lighted, small room.(Coordinate adjectives can be scrambled.)
9Do not use a comma between cumulative adjectives. Three large gray trucks tooled down the street.(Cumulative adjectives do not modify a noun separately.)Three gray large trucks rolled down the street.(Do not scramble cumulative adjectives.)
10Exercise 1.2: add or delete commas My brother and I found a dead snake picked it up and placed it on the teacher’s doorstep.For breakfast the children ordered rice doughnuts with peanut butter and chocolate milk.The region is not suited for large-scale agricultural activities such as planting pepper coffee cocoa candlenut and rubber or oil palm.An ambulance threaded its way through police cars fire trucks and irate citizens.
11Use commas to set off nonrestrictive elements The truck, with its horn blowing loudly, rushed through the streets of the city.This research, which I began two years ago, is beginning to show some interesting results.(Removing a nonrestrictive element does not greatly change the meaning of the sentence.)
12Do not use commas to set of restrictive elements. A laboratory that is well ventilated is needed for this type of research.The corner of the laboratory was filled with notebooks that dated from ten years ago.The novel “The Naked and the Dead” was Norman Mailer’s first novel.
13Use commas to set off transitional expressions. However, therefore, moreover, for example, as a matter of fact, in other wordsAs a matter of fact, many of the musicians have hearing problemsTherefore, they frequently need hearing assistance.
14If a transitional expression is between independent clauses, precede it with a semicolon (;) and follow it with a comma.Natural foods are not always salt free; for examples, celery contains more salt than most people would imagine.The new building is not completed; however, this classroom is air-conditioned.
15Use commas to set off parenthetical expressions. Evolution, as far as we know, doesn’t work this way.The fish weighed about five kilograms, give or take a few grams.Learning English, unfortunately for students, is a complex and frustrating process.
16Use commas to set off absolute phrases. Elvis Presley made music history in the 1950s, his records having sold more than ten million copies.The weather having become very bad, the airplane was unable to take off.(Of course, these two sentences could be written in another way)
17Use commas to set off contrasting elements. Sharp contrasts begin with words such as not, never, and unlike.Unlike Robert, Celia loved speech contests.We use alcohol, never water, to sterilize the instruments.
18Use commas to set off direct address, question tags, and interjections. Forgive us, Professor, for being late in sending our homework.Yes, but don’t do it again.This is the third time you have been late, isn’t it?Well, we sometimes have lots of other homework to do.
19Use commas to set off direct quotations. William Shakespeare, in “Twelfth Night”, said “God give them wisdom, that have it; and those that are fools, let them use their talents.”“I know not what course other may take, but, as for me, give me liberty or give me death”, said Patrick Henry before the American Revolution.
20Use commas to set off dates, addresses, titles, and numbers. The final examination will be on June 22, 2007.C. H. Wong, Ph.D., has been appointed to be the President of Academia Sinica.The teacher was born in Hualien, Taiwan, in 1960.The total price is NTD 23,456.
21Use commas to avoid confusion. To err is human; to forgive, divine.Of all the baseball games we played, this was the worst.All of the catastrophes that we feared might happen, happened.
22Exercise 1.3: add or delete commas We will do our work in the laboratory that is on the third floor.We will do our work in the chemistry laboratory which is on the third floor.The surprising thing however was the items that sold most quickly.Whenever the weather is rainy they wear raincoats and boots which keep them dry.Although, the air was warm, the water was too cold for swimming.Come to think of it more than forty years have passed since then.
23The Period Use a period to end a sentence. Bill asked whether our class will be cancelled tomorrow.The period is a red light or stop sign.“The period is the most powerful piece of punctuation at your disposal. In many scientific documents periods are not used often enough.” Michael Alley The craft of Scientific Writing
24Use a period to improve the flow of writing Use a period to improve the flow of writing. Sometimes, there are too many ideas packed into one sentence. Use periods and shorter sentences as follows to improve the flow and understanding.1. For temperatures above 1100K, the four fuels had about the same ignition delay when the ignition delay was defined as the time to recover the pressure loss from fuel evaporation, in spite of the large variations in ignition delay among the four fuels at lower temperatures.2. Ignition delay is the time required to recover the pressure loss from fuel evaporation. Despite the large variations in ignition delay at lower temperatures, the four fuels had about the same ignition delay for temperatures above 1100K.
25Use a period in conventional abbreviations. Mr. (mister); Mrs. (misses)Dr. (doctor); Ph.D. (Doctor of Philosophy)e.g. (exempli gratia); etc. (et cetera)i.e. (id est); p.s. (post scriptum)Sometimes the period is omitted in an abbreviation using capital letters:AM PMBA MADo not use a period in abbreviating names of organizations.UN USA WHOIBM FAO ILO