题目内容：

Where is the true home of the hamburger?

The kind of beef we see in hamburgers，minced(切碎的)beef，was possibly invented by Mongolians over 800 years ago.But who first put the beef in between pieces of bread and called it a hamburger? Three different cities in the United States all say that they were the first to invent America's favorite food.

Some people say that Fletcher Davis，from Athens，invented hamburgers.“Old Dave”，as people called him，was selling minced beef sandwiches in his lunch bar as early as the 1880s.Some years later，they say that a group of Germans called ①his sandwich a “hamburger” because people from the German city of Hamburg ate this kind of beef.

Other people believe that the hamburger came from a different American city.②Coincidentally，its name was also Hamburg.The Menches brothers were selling pork sandwiches at a fair in 1885，but when there was no more pork，they used minced beef and gave it a new name，the “hamburger”．

The third possible inventor of the hamburger was Charlie Nagreen，also known as “Hamburger Charlie”，from Seymour.He said that in 1885 he invented the world's first hamburgers.Seymour now celebrates the invention of the hamburger every year.In 1989，it was the home of the world's largest ever burger—over 2，500 kg!

根据短文内容，完成下列任务。

任务一：请根据短文内容，完成句子。每空一词。

1.When there was no more ____at the 1885 fair，the Menches brothers used minced beef _____．

任务二：请根据短文内容，猜测画线单词coincidentally的中文意思。

2.A. 幸运地    B. 碰巧地    C. 相反地

3.How often is the invention of the hamburger celebrated in Seymour?

__________________

任务四：请从文中找出与 Mongolians possibly invented minced beef a long time ago.意思相近的句子。

4._____________________________

任务五：请用英语简要概括出本文的主旨大意，不超过10个词。

5.It's mainly about _______．