2 . Wisdom teeth removal is common for many people in their late teens and early 20s. But why don’t they come in during childhood with the rest of our permanent teeth?

The answer comes down to child development. There’s not enough room in a child’s jaw for wisdom teeth.     1     So there’s more room for wisdom teeth to emerge.

However, many modern human jaws don’t grow long enough for wisdom teeth to come in. Ancient humans ate diets full of hard nuts, uncooked vegetables, and other tough foods.     2     But nowadays we have shifted to eating softer foods, meaning humans have shorter jaws than ancient humans do.

There is another reason wisdom teeth grow in later.     3     When ancient people would lose their molars (臼齿) from chewing tough food, wisdom teeth — the third set of molars — would take their place. But because most people don’t lose their molars as young children, wisdom teeth wait until adulthood to arrive.     4    

Nowadays, dentists often remove wisdom teeth because their emergence can cause pain in crowded mouths. Or it can cause problems and tooth damage later on.     5     But as a person gets older and their gums (牙龈) become weaker, their wisdom teeth may stick through. In this case, they tend to cause pain and needs removing.

A．Children have small jaws.

B．They’re not needed until then.

C．But as a kid grows, their jaw grows too.

D．Following this diet actually makes the jaw grow longer.

E．Most people have 32 teeth, including four wisdom teeth.

F．In other words, your wisdom teeth are programmed to erupt as a backup.

G．Not all wisdom teeth pop through the gums during the late teens and early 20s.

4 . If you’re a primate (灵长目动物) or a koala, you have something different compared to other animals: fingerprints. Now, a new study explains how our fingerprints help us keep a grip on the surfaces that we come into contact with — and it’s all to do with regulating moisture (水分). Researchers decided to investigate this using advanced laser imaging technology and discovered a finely tuned system controlling how wet or dry our fingertips are. That means our fingers are able to react to the various types of surfaces they’re pushed up against, making the grip as strong as possible with everything from a phone to an umbrella,and preventing “catastrophic slip”where we lose hold of objects.

Close-up (特写镜头) laser imaging of volunteers touching glass showed that when fingertips make contact with hard, impermeable surfaces, extra moisture is released to increase friction and grip. However, the sweat pores are eventually blocked off to avoid contacts that are too slippery.

This sweat-pore-blocking technique is combined with an accelerated evaporation process, controlled by the ridges (隆起) of the fingerprint, that comes into play when excessive moisture needs to be removed-again,with the ultimate aim of keeping a strong contact between finger and object.

Working together, the two biological mechanisms are able to adapt to surfaces whether our fingers are originally wet or dry: They provide the keratin(角质) skin layer with just the right amount of hydration (水合作用). That gives us skills that smooth-handed and smooth-footed animals don’t have.

Besides telling us more about the human body, the research is likely to help product designers who need to design a gadget (小装置) that humans need to interact with, such as a smartphone.

Further down the line, the findings might even benefit the development of grip on prosthetic (假体的) limbs and robotic equipment, as well as devices that are used to explore virtual reality environment (where the sensation of touch might need to be simulated).

1. Why does the author refer to a koala?

A．To explain different species are often in conflict.

B．To indicate people know little about its fingerprints.

C．To introduce the newly discovered function of fingerprints.

D．To highlight its reliance on fingerprints.

2. What does the underlined word “impermeable” in paragraph2 most probably mean?

A．Transparent.

B．Waterproof.

C．Uneven.

D．Invisible.

3. What can we infer from the text?

A．The sweat pores are closed for a while when we hold things.

B．The time when the sweat pores work is controlled by the ridges of the fingerprint.

C．The ridges of the fingerprint are insensitive to excessive moisture.

D．Prosthetic limbs and robotic equipment benefit most from the findings.

4. Which of the following is the best title for the text?

A．No Fingerprints, No Grip

B．Irreplaceable Benefits of Fingerprints

C．Two Biological Mechanisms Matter for a Grip

D．Fingerprints Give a Better Grip

8 . 阅读下面短文，在空白处填入1个适当的单词或括号内单词的正确形式。

Eyes are the window of our soul. We humans are only born    1    one set of eyes, so it is our job to take care of them. Almost all doctors agree    2    we can improve and maintain good eyesight by     3    (eat) lots of fresh vegetables. It is    4    (especial) important for us to eat vegetables like carrots and sweet potatoes.    5    , it is necessary    6    (protect) our eyes when we spend a long time in using computer, and we should take    7    short break every fifteen minutes to reduce the     8    (chance) of losing our eyesight. As the saying    9    (go), “It’s all fun and game, until someone loses an eye”. If you want to know more about protecting your eyes, please    10    (click)the following website.