The phrase "a large margin are" is not correct in written English.
It is incorrect because "are" does not agree in number with the singular noun "margin."
Example: "A large margin is necessary for this project to succeed."
Alternatives: "a significant margin is" or "a wide margin is".
By 1970, the most popular Dart model, by a large margin, was a two-door hardtop called the Swinger.
"And the fact that he did with such a large margin is a sign of real change _ at least let's hope so".
The winners of the event, by a large margin, were Lew Stansby of Castro Valley, Calif., a reigning world champion, and Ralph Katz of Chicago, a winner of several national titles.
The only time the temperature record was shattered by such a large margin was in the monster El Niño year of 1998.
And now, Bill de Blasio's success in the New York mayoral race, which he is leading by a large margin, is another indicator that social justice will be a serious electoral issue in the years to come.
The premise that Amazon can change its business model from selling other people's products at a razor-thin margin to selling other people's products at a large margin "is not credible," wrote Horace Dediu, an analyst with Asymco.
Winning Pennsylvania, and winning by a large margin, is important to the Clinton campaign's plan to convince superdelegates that Mrs. Clinton is the best choice for the Democratic party in the general election, Ms. Hesla said.
Djokovic, now No. 1 by a large margin, was even more imperious in the early rounds this year, but he lost his first set of the tournament in the fourth round, thanks to a brief fallow period and to the enduring combativeness of Lleyton Hewitt.
The competency that often stood out by a large margin was the leader's ability to keep a strategic perspective.
The top feed reader by a large margin is the much improved Google Reader, which is more popular than Yahoo and Bloglines combined.
