题干

小倩用如图所示器材探究影响导体电阻大小的因素,实验板上固定了四根金属丝.A、B、C的长度均为1m,D的长度为0.5m;A、B的横截面积相同,材料不同;B、C的材料相同,但横截面积不同;B、D的材料和横截面积都相同.下列说法中正确的是(   )

A:探究导体电阻大小与横截面积是否有关应选用B和C金属丝接入M、N两点间

B:探究导体电阻大小与导体长度是否有关应选用A和D金属丝接入M、N两点间

C:将B和D金属丝分别连入M、N两点间,连金属丝D时电流表示数大一些

D:该实验装置能探究导体电阻与导体材料是否有关

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A,C,D

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    Texting while walking is something that most of us are guilty of. We can't help replying to that message we just received. However, while it's fun to keep up with the latest gossip, we may actually be putting ourselves in danger.

    A team of researchers from two UK universities recently found that people who use their phones while on the move walk differently than usual.

    “Recently, a person in front of me was walking very slowly and weaving (迂回行进), and I thought, 'Is this person drunk?'” Matthew Timmis, co-author of the study, told the Guardian.

    It turned out that the person was just texting. Inspired by this, Timmis and his team set out to discover the effects of phone use on how we navigate streets.

    A group of 21 volunteers were asked to walk around a simulated (模拟的) street, complete with obstacles such as a step. The participants traveled the course a total of 12 times each, either writing or reading a message, making a call, or with no phone at all.

    It took the volunteers 118 percent longer to complete the course when using a phone. They also focused on the step obstacle 60 percent more and paid attention to the travel path 51 percent more when they weren't using a phone.

    Although there were no accidents, Timmis believes we should still be aware of what's going on around us.

    “The big risk here is suddenly-appearing hazards (危险), like a pedestrian (行人) suddenly walking in front of you,” he told the Guardian. “You are not going to be able to respond to that as efficiently, which increases the risk of injury.”

    To bring attention to the dangers of “text walking”, a temporary “texting lane” was set up in Antwerp, Belgium in 2015. And earlier this year, a special crosswalk featuring flashing red lights on the ground to get the attention of texters was set up in Wuhan, Hubei province.

    “Texting while walking can lead to collisions with poles or other pedestrians. You could even be endangering your own life when you cross the street without looking up,” a spokesperson for the company that made the Antwerp texting lane told Yahoo News.