题目内容：

Conventional wisdom says that hardship can make us old before our time. In fact, a new study suggests that violence not only leaves long-term scars on children’s bodies, but also changes their DNA, causing changes that are equal to seven to ten years of premature aging.

Scientists measured this by studying the ends of children’s chromosomes(染色体), called telomeres, says Idan Shalev, lead author of a study published in Molecular Psychiatry.

Telomeres are special DNA sequences which prevent the DNA in chromosomes from separating. They get shorter each time a cell divides, until a cell cannot divide any more and dies.

Several factors have been found to shorten telomeres, including smoking, radiation and psychological stresses such as being treated badly when young and taking care of a chronically ill person.

In this study, researchers examined whether exposure to violence could make children’s telomeres shorten faster than normal. They interviewed the mothers of 236 children at ages 5, 7 and 10, asking whether the youngsters had been exposed to domestic violence between the mother and her partner; physical maltreatment by an adult; or bullying. Researchers measured the children’s telomeres—in cells obtained by swabbing the insides of their cheeks—at ages 5 and 10.

Telomeres shortened faster in kids exposed to two or more types of violence, says Shalev. Unless that pattern changes, the study suggests, these kids could be expected to develop diseases of aging, such as heart attacks or memory loss, seven to 10 years earlier than their peers.

Shalev says there is hope for these kids. His study found that, in rare cases, telomeres can lengthen. Better nutrition, exercise and stress reduction are three things that may be able to lengthen telomeres, he says.

He study confirms a small but growing number of studies suggesting that early childhood adversity imprints itself in our chromosomes, says Charles Nelson, a professor of pediatrics and neuroscience at Harvard Medical School.

1.The new study found that ________.

A. violence leaves scars on a child’s mind

B. hardship can change a child’s aging

C. violence can speed up a child’s aging

D. hardship has a long-term effect on a child’s mind

2.According to the text, telomeres ________.

A. can make a cell die quickly

B. can help prevent DNA from separating

C. become shorter before they die

D. are at the ends of people’s chromosomes

3.All of the following things can shorten telomeres EXCEPT ________.

A. smokingB. cell divisionC. maltreatmentD. doing exercise

4.Which of the following is TRUE, according to the text?

A. Violence can cause quick cell division in children’s body.

B. Being treated badly will make a child’s telomeres shorten faster.

C. Researchers measured the children’s telomeres from their legs in the study.

D. Children who have shorter telomeres may have a heart attack earlier.

5.Which is the best title for the passage?

A. Violence Ages Children’s DNA

B. Children’s Changing DNA Patterns

C. Violence and Telomeres

D. the Function of Telomeres