III. Reading Comprehension: Questions 29-40. Read the following passage/report and choose the BEST ANSWER to each question.
A fingerprint is an impression of the ridges, or raised portions, of our fingers. When we touch certain surfaces, material from our fingers is left
behind and fingerprints remain. The police can use such fingerprints to identify the people who left them. This is because no two people—not even
identical twins—have the same fingerprints.
Scientists who analyze fingerprints have classified them into three types: latent, patent, and plastic. Latent prints may show only a small portion of
the finger and may be smudged or distorted, depending on how they were made. This kind of print is not reliable for the police to establish a person’s
identity. Patent prints are ridge impressions which are easily seen by human eyes. Since these prints are already visible, they are generally
photographed. A plastic print is a ridge impression that has been pressed into a material that retains the shape of the ridges. Examples of these prints are commonly found in melted candle wax and grease on car parts. These prints are also easy to see, but they may be accompanied by latent prints of other people, so investigators have to examine them carefully.
Although there are hundreds of reported techniques for fingerprint detection, only about twenty are really effective and currently being used.
Some involve using a chemical that reacts with the amino acids in the print; other methods depend on a powder sticking to oily or watery print deposits.
As technology improves, so does fingerprint detection. This is bad news for criminals who think they can simply wipe away their fingerprints and not
be identified by the police.