Your cell phone holds secrets about you. Besides the names and numbers that you’ve program

Your cell phone holds secrets about you. Besides the names and numbers that you’ve programmed into it, traces of your DNA remain on it, according to a new study.
DNA is genetic material that appears in every cell. Like your fingerprint, your DNA is unique to you --- unless you have an identical twin. Scientists today usually analyze DNA in blood, saliva(唾液), or hair left behind at the scene of a crime. The results often help detectives identify criminals and their victims.
Meghan J. McFadden, a biologist at McMaster University in Hamilton, Ontario, heard about a crime in which the suspect bled onto a cell phone and later dropped the device. This made her wonder whether traces of DNA remained on cell phones --- even when no blood was involved. To find out, she and a colleague collected flip-style(翻盖式) phones from 10 volunteers. They collected invisible traces of the users from two parts of the phone: the outside, where the user holds it, and the speaker, which is placed at the user’s ear.
The scientists scrubbed(meaning “cleaned”) the phones using a liquid mixture made mostly of alcohol. The aim of washing was to remove all detectable traces of DNA. The owners got their phones back for another week. Then the researchers collected the phones and repeated collecting traces on each phone once more. They discovered DNA that belonged to the phone’s owner on each of the phones.
Surprisingly, DNA showed up even in swabs that were taken immediately after the phones were cleaned. That suggests that washing won’t remove all traces of evidence from a criminal’s cell phone. So cell phones can now be added to the list of clues that can help a crime-scene investigation.
【小题1】McFadden decided to find out whether people leave their DNA on their cell phones when she . A．got her cell phone lost by chanceB．found a cell phone with blood on itC．heard about a crime involving a cell phoneD．did research on cell phones【小题2】The scientists allowed the volunteers to keep their cell phones for a week in order to . A．let them leave their traces on their phonesB．avoid keeping their cell phones too longC．give them a chance to get rid of their secretsD．find out who is responsible for the crime【小题3】The last paragraph mainly tells us that cell phones . A．do harm to peopleB．should be often cleanedC．disclose people’s secretsD．help deal with crimes【小题4】Which of the following is NOT mentioned in the passage?A．The reason for collecting the phones from volunteers. B．The technique of collecting DNA on the phones. C．The method of removing traces of DNA on the phones. D．The purpose of washing the cell phones.C

(答案→)C 解析：可联系答.案.网客服索取。

感谢回答，我学习了