题目内容：

    The amount of time young children in the United States spend with mobile screens might raise some eyebrows, as a new report found it has tripled in just four years.

Children 8 and younger spent about 15 minutes a day staring at a mobile screen in 2013 and now they spend 48 minutes a day, according to the report by Common Sense Media, a nonprofit organization focused on helping children, parents, and educators navigate the world of media and technology.

The report, released on Thursday, also found that 42% of children 8 and younger now have their own tablet devices, a sharp increase from 7% four years ago and less than 1% in 2011.

Children spending more time on mobile devices comes as no shock to Douglas Gentile, a psychology professor at Iowa State University who was not involved in the new report but has studied the effects of media use on children.

“On the one hand, it's not surprising because it's what we look around ourselves and can see.I can see it at the airport, for example, I can see it at restaurants and I can even see it in my own home where my younger daughter watches almost no television, but she'll watch lots of TV shows on her phone, "Gentile said.

“On the other hand, it's been getting harder for parents to really monitor a lot of what their kids are seeing and doing.At the same time, they're relying on the seeming benefit of being able to quiet the kid at a restaurant with a device,” he said. “We may be building a bit of a Frankenstein’s monster, because we re using that power for our benefit, not for the child’s benefit.”

These changing patterns in how children interact with media appear to be great, said James Steyer, chief executive officer and founder of Common Sense Media.in an email to CNN. “One of the most shocking findings is that mobile devices are now as popular in the home as TVs-98% of households with kids under 8 have a mobile device,” he said. “The ubiquity of mobile is changing childhood.”

1.The writer uses figures in the second paragraph to_________.

A.prove the reliability of the report.

B.praise the efforts made by Common Sense Media.

C.indicate the popular use of mobile devices nowadays.

D.illustrate the increase of time children spend on mobile devices.

2.According to Douglas Gentile, parents_________.

A.can totally control children's use of mobile devices .

B.always use mobile devices in favor of their children.

C.partly cause children's increasing use of mobile devices.

D.often discourage their children from using mobile devices.

3.The underlined word in the last paragraph most probably means “_________”.

A.rare use. B.important role.

C.obvious benefit D.common existence