题目内容：

    Three boys were enjoying themselves in their hometown of Bovina, Mississippi. However, their lives were turned upside down when they discovered the jawbone of a Mastodon (齿乳象).

Brothers Shawn and Caid Sellers and cousin Michael Mahalitc found the prehistoric bone in a piece of earth that was recently plowed (犁、耕). “I thought it was a log,” Caid said. “I tried to pick it up and it was really heavy and I saw teeth on it.” The bone weighed about 50 pounds. They eventually got the bone to their home and fitted it in their tub (浴盆), but it took their collective strength, might and a golf cart, to carry the large Mastodon bone.

“They didn’t expect to find that,” Michael’s mom said. “Now that they have, I believe that they will be more aware of their surroundings and what they’re digging up when they are digging and playing.”

“We’ve gotten a lot of petrified (石化的) wood and Civil War relics from the area and that’s what I thought it was,” the brothers’ mother said. “This is our first set of teeth we’ve found. So we thought it was their imagination. We were quite surprised to see that it was not their imagination.”

They were exploring near the brothers’ home. Lo and behold (真想不到), they saw what they thought resembled a fossil. It was the curator of paleontology (古生物负责人) of the Mississippi Museum of Natural Science, George Phillips, who first identified the bone as a “very mature individual.”

The Mastodon was a mammal who lived during the prehistoric times. They had long tusks and trunks, like elephants. They were clearly different from their modern-day counterparts, as well as woolly mammoths (猛犸).

1.How did they find the jawbone of a Mastodon?

A.With great efforts. B.By chance.

C.Instructed by an expert. D.Through imagination.

2.At first the brothers’ mother thought the jawbone was________.

A.from people who died in the Civil War B.the bone from a very mature individual

C.like a log or something D.the prehistoric bone

3.The discovery of the jawbone of a Mastodon is important mainly because it________.

A.helps people to know more about the Civil War

B.teaches kids to be more aware of their surroundings

C.promotes the research on more prehistoric creatures

D.attracts the Mississippi Museum of Natural Science

4.Which of the following can be the best title for the article?

A.Prehistoric Bones Recently Found in Mississippi

B.Not Petrified Wood Nor Civil War Relics

C.First Identifying Bone as a “Very Mature Individual”

D.Unexpectedly Discovering Mastodon Jawbone