Lie detector is a device that helps determine whether a person is telling the truth. A lie detector, also called a polygraph

Lie detector is a device that helps determine whether a person is telling the truth. A lie detector, also called a polygraph, records physical changes that occur   16   questions. Such changes include alterations in the blood pressure, pulse   17   , perspiration (出汗), and       respiration (呼吸) that may occur when an individual lies. It helps police and other _ 18    question suspects about their possible involvement in a    19    .

Polygraph experts and other supporters of lie detector testing believe that such tests are highly accurate. Some criminal cases arc decided on the basis of lie detector tests,  20  can be used as evidence if all people  21  agree beforehand to their use. A person who agrees to do so is connected to a polygraph and sits in a chair while answering questions. The lie detector makes a continuous    22   of body functions by drawing lines on a moving graph. Some of the questions asked during a lie detector test are related 23 the matter being investigated. Others are unrelated or only   24   related, but they are included to improve the test’s    25   . Each question must be answered yes or no. If a person lies, the graph normally records a physical change. This change occurs because of the person’s   26    response to telling a lie. After the test, a tic detector examiner  27  the test results.But many legal experts believe that testimony obtained with the aid of tic detectors is not accurate enough to be used    28__. These experts also say that such testimony may   29   the legal principle which can protect people   30   testifying against themselves. The judges in most criminal cases do not permit testimony obtained with lie detectors to be used as evidence.

第（30）空

A.for

B.in

C.with

D.from

正确答案是D