题目内容：

    Corn has been a significant part in American food since before European arrival. After the Civil War, grits (粗玉米粉), which is made out of corn, became a diet mainstay (支柱) because water-powered mills (磨坊) worked to grind dried corn. They were relatively inexpensive and could be eaten with almost anything, making it possible for everyone to enjoy.

Grits are usually cooked with water, cream and butter over the course of many hours. There can be varying types of grits from smooth to grainy. There are even instant grits for those without the hours to cook. Worth noting is that sugar is not typically added.

Grits can be served for breakfast, lunch and dinner, but they're commonly used as a base, usually topped with seafood and a delicious sauce. It's a dish eaten by everyone from sitting presidents to blue collar workers in a variety of ways, both in fine dining restaurants and oily spoons.

Shrimp and grits is the most well-known dish incorporating grits, especially in coastal areas like Charleston, South Carolina. It was originally a fisherman’s breakfast, a hearty meal before a long day of work, and today, it's found on menus throughout the nation.

Chefs have also become creative with the dish, adding modern elements to the traditional. Mashama Bailey has a foie gras (鹅肝酱)  and grits dish at The Grey in Savannah, Georgia. Edward Lee has prepared it like the porridge his Korean parents cooked during his growing up, but uses Kentucky's Wiesenberger grits. Nathalie Dupree has made her career on the dish with her cookbook titled “Shrimp and Grits," while Virginia Willis has the appropriately titled “Grits”.

1.Why did grits become main food?

A.Because corm played a key role.

B.Because dried corn was extremely cheap.

C.Because the Civil War broke out.

D.Because water-powered mills turned up.

2.What can we learn about grits from Paragraph 3?

A.They are popular among all walks of life.

B.They are smooth to feel.

C.They are placed on top of other foods.

D.They are expensive to purchase.

3.What breakfast did South Carolina fishermen like?

A.Grits with shrimp. B.Grits with sugar.

C.Grits with butter. D.Grits with cream.

4.Why does the author mention Lee's parents?

A.To introduce Lee's upbringing experiences. B.To promote Lee's cooking techniques.

C.To explain a modern flavour of grits. D.To advertise a newly-published cookbook.