发布日期：02-06 18:39 分类：英语 阅读次数：26
摘要Punctuation 1. Commas Use a comma before and, but, so, yet, or, and nor when tho ...
Use a comma before and, but, so, yet, or, and nor when those words are used to join two main clauses.
I think that Doré’s illustrations of Dante’s Divine Comedy are excellent,- but my favorite drawing is “Don Quixote in His Library.”
Practically all nitrates are crystalline and readily soluble,- and they are characterized by marked decrepitation when heated on charcoals by a blowpipe.
The general rule stated above should be qualified in two respects. First, when the two clauses joined by the conjunction are very short, the comma is optional. In the following example, both sentences are correct.
The door was ajar and the house had been ransacked.
The door was ajar,- and the house had been ransacked.
Second, if either clause itself contains commas, you may need to use a semicolon before the con-junction for clarity.
Because many diseases and insects cause serious damage to crops, special national legislation
has been passed to provide for the quarantine of imported plants; and under provisions of
various acts, inspectors are placed at ports of entry to prevent smugglers from bringing in plants that might be dangerous.
Given the length of the two clauses and the fact that each clause contains a comma, you should use a semicolon following plants, rather than a comma.
Use commas to separate the elements of a series.
A full train crew consists of a motorman,- a brakeman,- a conductor,- and two ticket takers.
The procedure requires that you open the outer cover plate,- remove the thermostat,- replace the broken switch,- and then replace the thermostat.
Use a comma to separate a subordinate clause at the beginning of a sentence from the main clause.
After Peter finished painting the bird feeder,- he and Jack hung it from a limb of the oak tree.
When Pat explained to his mother that ten was the highest mark given on the entrance test,- she breathed a sigh of relief.
If the subordinate clause follows the main clause, you do not need to set it off with a comma.
Tim hopes to score well on the exam because he plans to go to an Ivy League school.
Use a comma after a long introductory phrase.
In this impoverished region with its arid soil,- a typical diet may contain only 800 calories per day.
At the height of the moral war against sensational journalism,- Horace Greeley moved into the forefront of the journalistic picture.
Regardless of their length, use a comma after introductory gerunds, participles, and infinitives.
Begun in 1981 and completed in 1985,- the bridge provided the first link between the island and the mainland.
To slow the bleeding,- Van tied a tourniquet around the lower portion of the leg.
Use commas to set off nonrestrictive clauses and phrases and other parenthetical elements.
Niagara Falls,- which forms part of the border between the United States and Canada,- was the site of a saw mill built by the French in 1725.
The second Nicene Council,- the seventh ecumenical council of the Church,- was summoned by the Empress Irene and her son Constantine.
The last hope of the French expired when Metz,- along with 180,000 soldiers,- was surrendered by Bazaine.
Secretary of State Acheson,- however,- made a reasoned defense of the treaty.
(Nonrestrictive clauses and phrases are ones not essential to the meaning of the main clause. In general, if you can omit the material without changing the meaning of the main clause, then the material is nonrestrictive and should be set off by commas.)
These rules summarize the most important uses of commas. If you use them in just these situations, then you won’t make a mistake in their use. In particular, do NOT use commas in the following situations.
Do not use a comma to separate a subject from its verb.
Until the end of the eighteenth century, the only musicians in Norway,- were simple, unsophisti-cated peasants who traveled about.
(The underlined comma is incorrect.)
Do not use commas to set off restrictive or necessary clauses or phrases.
Prizes will be awarded in each event, and the participant,- who compiles the greatest overall total,- will receive a special prize.
Since learning of the dangers of caffeine, neither my wife nor I have consumed any beverage,-containing caffeine.
(The underlined commas are incorrect.)
Do not use a comma in place of a conjunction.
After months of separation, Gauguin finally joined Van Gogh in Arles in October of 1888, Gauguin left a few weeks later.
The sentence is incorrect because clauses cannot be spliced together using only a comma. If you want to join two main clauses, you can use a conjunction (such as and ) plus a comma or semicolon or even just a semicolon. The sentence above could have been written: “After months of separation, Gauguin finally joined Van Gogh in Arles in October of 1888, but he left a few weeks later.”
One use of the semicolon has already been mentioned: use a semicolon between main clauses linked by a coordinate conjunction (and, but, etc.) when the main clauses are complex; e.g., when they them-selves contain commas. (See above.) Another use of semicolons is to separate two main clauses that are not linked by a coordinate conjunction.
He grew up on a farm in Nebraska; he is now the captain of a Navy ship.
The Smithtown players cheered the referee’s decision; the Stonybrook players booed it.
Notice that in these examples, each clause separated by the semicolon could stand alone as an independent sentence:
He grew up on a farm in Nebraska. He is now the captain of a Navy ship.
The Smithtown players cheered the referee’s decision. The Stonybrook players booed it.
Unless each clause can function as an independent sentence, it probably is wrong to use a semicolon.
When John entered the room; everyone stood up.
Clem announced that the prize would be donated to Harbus House; a well-known charity.
The semicolons in the examples above are used incorrectly. Notice that the elements separated by the semicolons cannot stand as independent sentences. These sentences can be corrected by using com-mas in place of the semicolons.
A colon may be used to introduce or to call attention to elaboration or explanation.
The teacher announced that the course would require three papers: one on Shakespeare, one on Dickens, and one on a contemporary writer.
Will’s suggestion was truly democratic: let everyone serve as chair for one meeting.
Be careful not to use a colon to introduce or call attention to material that is already signaled by some other element of the sentence.
The seemingly tranquil lane has been the scene of many crimes including: two assaults, three robberies, and one murder.
In addition to test scores, college admissions officers take into consideration many other factors such as: grades, extracurricular activities, and letters of recommendation.
In each example, the colon is used incorrectly because the special material is already signaled by some other element in the sentence. These sentences are correctly written as follows:
The seemingly tranquil lane has been the scene of many crimes, including two assaults, three robberies, and one murder.
In addition to test scores, college admissions officers take into consideration many other factors such as grades, extracurricular activities, and letters of recommendation.
The only use you should have for a period on the test is to mark the end of a sentence. Make sure, however, that any underlined material that includes a period does not create a sentence fragment.
Peter notified Elaine. The guidance counselor, that he had been accepted.
The first period creates a sentence fragment out of what follows. The sentence can be cor-rected as follows:
Peter notified Elaine, the guidance counselor, that he had been accepted.
Dashes can be used to set off for emphasis or clarity an explanatory, illustrative, or parenthetical remark.
Careful attention to the details of one’s personal appearance—neatly pressed clothing, shined shoes, and well-groomed hair—is an important part of preparing for a job interview.
Many colleges—including the nation’s top schools—set aside a certain number of first-year places for students who show academic promise in spite of low test scores.
Peanuts—blanched or lightly roasted—add an interesting texture and taste to garden salads.
The dashes in the sentences above have a function similar to commas when they are used to set off parenthetical remarks. The difference between the two is a matter of emphasis. The dashes mark a more dramatic shift or interruption of thought. Do not, however, mix dashes and commas:
Peanuts—blanched or lightly roasted, add an interesting texture and taste to garden salads.
The example above is incorrect. You must use either two dashes or two commas.