标点在修正 run-on sentence 的作用

OG-purple:

        Run-on sentences: A run-on sentence is
two independent clauses that run together without proper punctuation.

Example:

        Correct: Jose Canseco is still a feared
batter, most pitchers don't want to face him.”

        Incorrect: "Jose Canseco is still a
feared batter most pitchers don't want to face him.”

http://www.uni.edu/~petersc/runon.htm:

            6) Revise run-on sentences (including comma-splices).
                    
        
        Run on sentences are composed of two or more independent
clauses that aren’t joined together properly. Independent clauses may be
joined together either by a
comma and a
coordinating conjunction (and, but, or, nor, for, so, yet), or by a semicolon.
Alternatively, one may make the clauses into separate sentences, or restructure
the sentence.

Below are two examples of run-on sentences:

Most of the candidates had lined up endorsements from leaders of their party,
Skinner had not.

Most of the candidates had lined up endorsements from leaders of their party,
however, Skinner had not.

And here are the four possible ways to fix them, mentioned above:

Most of the candidates had lined up endorsements from leaders of their party, but Skinner had not.

Most of the candidates had lined up endorsements from leaders of their party; however Skinner had
not.

Most of the candidates had lined up endorsements from leaders of their party. Skinner had not.

        Whereas most of the
candidates had lined up endorsements from leaders of their party, Skinner had not.

OG11-verbal-2. However
much United
  States voters may agree that there is waste in government and that the government
as a whole spends beyond its means, it is difficult to find broad support for a
movement toward a minimal state.

        (A) However much United
States voters may agree that

(B) Despite the agreement among United States
voters to the fact

(C) Although United States
voters agree

(D) Even though United States
voters may agree

(E) There is agreement among United States
voters that

Parallelism + Grammatical construction

        In this correctly written sentence,
parallel subordinate clauses are followed by a main clause. These parallel
subordinate clauses are both introduced by that: that there is … and that the
government …

A Correct. In this sentence, the repetition of that to introduce two
subordinate clauses makes the construction parallel and correct.

E Using two independent clauses separated only by a comma creates a "run-on sentence"; the sense of the
sentence is changed by the omission of may.

The correct answer is A.

Another example:　ｂｙ　思故

http://forum.chasedream.com/dispbbs.asp?boardID=23&ID=226476&page=1

OLD_OG135. Intar, the oldest Hispanic theater company in New
  York, has moved away from the Spanish classics and now
it draws on the works both of contemporary Hispanic authors who live abroad and
of those in the United States.

(A) now it draws on the works both of contemporary Hispanic
authors who live abroad and of

(B) now draws on the works of contemporary Hispanic authors,
both those who live abroad and those who live

(C) it draws on the works of contemporary Hispanic authors
now, both those living abroad and who live

(D) draws now on the works both of contemporary Hispanic
authors living abroad and who are

(E) draws on the works now of both contemporary Hispanic
authors living abroad and those

In choices A and C, it intrudes between the halves of the compound verb
        has moved... and [now] draws to introduce a new grammatical
subject, thereby creating a
run-on sentence: the inclusion of it requires a comma after classics to set off the new independent
clause. The placement of now is awkward in C, and the construction living
abroad... and who is not parallel in C and D. Misplacement of words creates
ambiguity in E: for example, the positioning of both immediately before the
phrase describing the authors suggests that there are only two contemporary Hispanic
authors living abroad. The logical word placement and parallel phrasing of B,
the best choice, resolve such confusions.

http://homepages.uhwo.hawaii.edu

Run-on Sentences and
Comma Splices

A run-on sentence results when two independent clauses are joined
without a conjunction or without punctuation. A comma splice results when two independent clauses are mistakenly
connected with a comma instead of being separated into two sentences
or joined with a conjunction
        or a semicolon. Run-on sentences and
comma splices should be avoided for the same reasons that sentence fragments
should be avoided: they are hard to read, they confuse the reader, they suggest
that you are careless, and they indicate that you do not know what a sentence
is.

Revising Run-on
Sentences and Comma Splices

There are several ways to revise run-on sentences and
comma splices: by using a period between the independent clauses, by inserting
a semicolon between the independent clauses, by placing a comma and a
coordinating conjunction between the independent clauses, or by using a
subordinating word to make an independent clause a dependent clause. For
example:

• Use a comma and a
       coordinating conjunction (and, but, yet, nor, for, or, so) between
       independent clauses.

Example: The physicist Marie Curie
discovered radium, and she won two Nobel Prizes.

• Use a period or a semicolon
       between the independent clauses.

Example: The physicist Marie Curie
discovered radium. She won two Nobel Prizes.

The physicist Marie Curie
discovered radium; she won two Nobel Prizes.

• Use a semicolon plus a
       conjunctive adverb (also, furthermore, however, nevertheless,
       similarly, therefore, next, finally, indeed, certainly) or a transitional
       expression (as a result, in fact, at the same time, in conclusion) between
       the independent clauses.

Example: Marie Curie and her
husband, Pierre, worked together at first; however, he died at age 47.

• Revise one independent
       clause into a dependent clause.

Example: Radium, which can cause cancer,
is also used to cure cancer.

還是不明白，為什么OG在講解run-on sentence的時候舉的這個例子中間只用逗號隔開，而在OG11-verbal-2里的E項中又指出“using 2 independent clauses separated only by a comma creates a run-on sentence"?

请帮我解答一下问题吧，谢谢，或者告诉我到哪里找答案