题目内容：

A quarter of today’s UK children are living in families which cause more than one risk to their educational development, a study says.

Institute of Education researchers analyzed 10 risk factors affecting more than 18,000 families. Risks included financial stress, teenage parenthood, depression, low skills and alcohol abuse. Previous research suggests families with multiple risk factors are the most damaging. According to the research, just over four in ten people experienced no risk factors in their early childhood, while a third faced only one. It would mean 192.000 UK children born 10 years ago have been growing up in families with multiple risks to their development.

The paper's authors found that those who had grown up with two or more risk factors had poorer behavioral development scores at ages three and five. They also did worse in standard vocabulary tests at these ages. The report, published by the Centre for Longitudinal Studies, said. “Children living in families with both multiple risks and low income faced the worst across most developmental outcomes.”

“These children achieved the lowest change in vocabulary test scores between ages three and five.” Professor Dex added. “The most reassuring thing is that if you come into contact with just one of these risk factors, there is a fairly modest effect on children. She suggested that health visitors could be aware of families where there were two or more of these indicators, and offer help. ”

The government has pledged to turn around the lives of England's 120.000 most troubled families by 2015. To qualify for help, the families need to meet five out of seven criteria including truanting (旷课的）children, parents with addiction and anti -social behavior.

1.According to the research, what families are the most damaging to children's educational development?

A. Families with no risk factors.

B. Families with two or more children.

C. Families with two or more risk factors.

D. Families with the only financial stress.

2.What can we learn about the children growing up with multiple risk factors?

A. They didn't care about developmental outcomes.

B. They had poorer behavioral development in high school.

C. They tended to behave better in dealing with different risks.

D. They tended to perform worse in vocabulary tests in their early childhood.

3.The underlined word “pledged” in the last paragraph can be replaced by__________ .

A. promised    B. refused

C. hesitated    D. failed