Sunscreens can offer protection from two types of ultraviolet (UV) rays : UVB, which according to the Skin Cancer Foundation, are the chief cause of sunburn and play a key role in the development of skin cancer, and UVA, which get through the skin more deeply and are largely responsible for skin aging and wrinkling, as well as skin cancer risk. The SPF measurement on sunscreens refers to the UVB protection level -- and the number may not mean what you think it does. SPF 15 doesn't protect you from 15% of UVB rays, just as SPF 100 doesn't protect you from 100% of the rays. In fact, as you get into the higher numbered SPF sunscreens (think: 50 and above), the difference in UVB protection is actually pretty small. Theoretically, though the increase in UVB protection with a super-high SPF sunscreen may be not worth considering, it may help, and certainly can't hurt, to use it -- that is, as long as you do so correctly. "The only _ is whether you're giving yourself a sense of false security," Dr. Gohara says. Indeed, as Dr. Wang also pointed out, when people choose increased SPFs, they may actually feel so protected by the product that they finally ignore proper sun protection. "When people use really high SPF products, they tend not to reuse, they tend to stay out in the sun much longer, and they don't use other protective measures such as clothing and hats," he says. Regardless of any increase in protection that a high SPF may or may not offer, one thing is certain: It doesn't give your body a free pass from sunburns, aging, or cancers, and it doesn't protect you from those things for any greater length of time than the lower SPF options. Both Dr. Wang and Dr. Gohara emphasized that, no matter what the SPF is, it's important to reapply your sunscreen every two hours. Why are we advised to reapply our sunscreen every two hours? A) We choose too low SPF products. B) The higher SPF can make us stay outside longer. C) Clothing and hats are not enough for sun protection. D) It can't completely protect us from aging, sunburns or cancers.
D
(Question)
Dogs and cats are not for students who live in the dormitory. Just think about the noise, the smell and all that wild behavior--chewing on whatever they can get their teeth on, or knocking over the trash can. But don't feel sad. There are smaller and less destructive pets to make your dormitory life colorful. Betta fish They make great pets with their big personality and astonishing colors, ranging from bright red, dark blue to lemon yellow. Unlike many fish, most bettas react to their owner's presence and become more active when they are nearby, which is unusual in the fish world. Chinchillas Without bad smell, about the size of a rabbit and with fur so dense that they can't get pests such as fleas , the friendly creature originally from the Andes Mountains in South America makes an ideal indoor pet. Chinchillas are very social animals, so if you only have one, you will become its family. In cold winter days, in a glance at this fury pet in a dorm will bring you a lot of warmth. Land hermit crabs In a society where owners are often asked "Are they tasty?", land hermit crabs are among the most unlucky animals commonly kept as pets. But they are easy to care for, inexpensive and fascinating to watch. And the fact that they don't cause any allergic reactions makes them perfect for college dormitories. Red-eared sliders If you're interested in a lifelong friend, a red-eared slider makes a wonderful pet. If well cared for, they can live for around 40 years. But there are a couple of things you should know. Red-eared can grow to an adult size of up to 30cm! So you may need a larger tank quickly. In addition, you will need to provide UV lighting, water heater, and a swimming area and a basking area. Housing a red eared slider is not easy. If you want to keep the pet as long as possible, you'd better choose _ . A) Betta fish B) Chinchillas C) Land hermit crabs D) Red-eared sliders
(Answer)
D
Have you seen a yellow-and-black salamander ? How about a scarlet frog? Scientists haven't spotted either species in more than 20 years. What happened to them? Are the creatures still out there, or are they extinct? Those are questions that scientists hope to answer. They recently set out around the world in search of those and other long-missing amphibians. An amphibian is an animal that spends part of its life in water and part on land. Frog, toads , and salamanders are amphibians. The experts are looking for about 100 species. They are searching at least 14 countries on five continents. They will look for the salamander in North America. They hope to find the scarlet frog in South America. They're also looking for species in Africa, Asia and Australia. Scientists are hopeful that they'll find the amphibians--and soon! If the creatures are out there, they may need help. Many amphibians are endangered. The animals face many dangers including pollution and diseases. People cut down the forests where they live. "If researchers can find the missing creatures, they might be able to figure out how to save them," explains expert Robin Moore. He began searching for the amphibians earlier this month. "This search will tell us a lot about how amphibians are doing," Moore told WR News. "I don't know what we will find, but that makes the search even more exciting." Lost in the Wild Scientists' hunt for missing amphibians is under way. Read about some of the species they hope to find. Turkestanian salamander This salamander is a mystery to scientists. Experts found a few of them more than 100 years ago, but none have been seen ever since. Gastric brooding frog Experts first discovered this frog in 1914 in eastern Australia. It may be extinct because of disease and habitat loss. Rio Pescado stubfoot toad Last sighting: 1995, in South America Scientists hope to find this spotted toad in rivers and rainforests in Ecuador. The animal faces threats including pollution and disease. It can be learned from the passage that _ . A) the scarlet frog used to live in Africa B) researchers have no way to save amphibians C) the scientists will search 14 countries at most D) Robin Moore has begun his search for amphibians
D