1 . Predator-Prey Interactions Shape Evolutionary Adaptations

To survive, predators must eat and prey must avoid becoming food. Therefore, predator and prey populations exert intense environmental pressure on one another, resulting in coevolution. As prey become more difficult to catch, predators must become more adept at hunting. Coevolution has given the mountain lion sharp claws, and it has given the fawn the mountain lion hunts the behavior of lying still as it awaits its mother. It has produced the keen eyesight of the hawk and the earthy camouflage coloration of its small mammal prey. Coevolution of predators and prey has also given rise to the bright colors of the poison arrow frog and the coral snake. In the next section, we examine an example of the evolutionary results of predator-prey interactions.

Some Predators and Prey Have Evolved Counteracting Behaviors

Bat and moth adaptations provide an excellent example of how both physical structures and behaviors are molded by coevolution. Both bats and moths are nocturnal (they are quiet during the day and active at night), and bats hunt moths as prey. Bats have evolved a system for sensing their surroundings at night, called echolocation. In echolocation, bats emit very high-pitched and high-frequency sound pulses that only they can hear. The bats navigate and hunt by listening to the sound as it reflects off surrounding surfaces and then by interpreting the returning echoes as a mental image. In response, some species of moths have evolved simple ears (most insects do not have ears) that are able to detect the sounds that bats use in echolocation. When they hear a bat, these moths change their flying patterns, flying erratically or dropping to the ground. The bats, in turn, have evolved the ability to change their sound pulses to a range that the moths cannot hear. Some moths have evolved a way to interfere with the bats’ echolocation by producing their own high frequency clicks. In response, when hunting a clicking moth, a bat may turn off its own sound pulses temporarily and locate the moth by following the moth’s clicks.

Each morning, amateur    1     (cycle) Cui Yue rides his bicycle along the Tanglai Canal in Yinchuan, capital of northwest China’s Ningxia Hui. Autonomous Region, to enjoy the picturesque natural scenery. Born and    2    (raise) in the city, 68-year-old Cui said cycling along the canal allows him to experience the city’s improving ecology after several waterfront parks were built in recent years.

The over-2,000-year-old canal that Cui     3    (frequent) was built during tne Han Dynasty, aimed at bringing the Yellow River water to present day Ningxia    4    helping him the region with vast deserts into farmland. The canal    5    (include）in the World Heritage Irrigation Structures in 2017. Through the ages, it is still functioning     6    an ecological corridor and is the largest    7     (natural) flowing trunk canal in the Yellow River irrigation area.

Along the canal’s 75-km section    8    (run) through urban Yinchuan, several parks have been built with walking and cycling routes, contributing to the city’s expanding green space mapped out for public leisure. In the city’s rural areas, the canal is a water source for farms and wetlands,playing a role in    9    (agriculture) development and ecological protection. It is also one of the water sources for wetlands and a large artificial lake,    10     have become habitats for hundreds of migratory bird species.

5 . For these four English boys, the hardest part about living on their own was their landlord’s (房东) NO-PETS policy. They had just moved into a shared apartment in Bristol, England and were _______ to learn that animals were not allowed.

When they saw an energetic young Labrador in the neighbor’s window, _______, they got an idea. The four friends quickly wrote a letter to the dog’s owner, expressing their _______ to let them play with the dog.

“If you ever need someone to _______ him/her, we will gladly do so,” they wrote. “If you ever get _______, we are more than happy to look after him/her. Our landlord won’t _______ pets, and we’ve all grown up with animals,” the letter read. “The adult life is a _______ without one.”

The roommates left the _______ in the neighbor’s mailbox. Surprisingly, they received a response directly from Stevie Ticks, the dog!

“What a pleasure it was to receive your letter,” wrote Stevie Ticks (as dictated by her owner). “It would be great if we could be friends. I must warn you that the _______ of my friendship is 5 ball throws a day.” To their delight, the neighbor was true to the word and the boys were ________ to play with the friendly 2-year-old dog.

6 . A newly developed disposable paper battery promises to make a big impact on single-use electronics. The battery that has been demonstrated by researchers is biodegradable (可生物降解的), made from sustainable materials, and cheap to put together. What’s more, it can be produced in a variety of shapes and sizes as needed.

To give an idea of the power, a two-cell battery was enough to power an LCD alarm clock. While it won’t be charging up your computer anytime soon, there’s lots of potential for low-powered sensors. “We present a printed paper battery developed to power single-use disposable electronics and to reduce their environmental impact to the lowest level,” write the researchers in their published paper.

The battery is based on a metal-air electrochemical cell. Made from sodium chloride salt-diffused (氯化钠盐扩散的) paper, it can measure as little as one square centimeter, and is based on printed inks. All that’s needed, then, is a small amount of water, as little as two drops. This dissolves the salts within the paper, and then activates the battery as they travel. The battery starts producing power around 20 seconds after water is added, according to the experiments carried out by the team.

Although the performance decreases over time as the paper dries out, it can be topped up to some extent with more water. The researchers say they want to improve the efficiency of the battery in the future, and get it working for longer.

“With a rising awareness of the e-waste problem and the emergence of single-use electronics for applications, there is a growing need for low environmental impact batteries,” write the researchers.

Originally constructed around 256 BCE by the State of Qin     1     an irrigation and flood control system, Dujiangyan is a remarkable example of ancient engineering skill and is still     2     use today.

During the Warring States period, people who lived along the banks of the Min River     3     (trouble) by annual flooding. Qin governor and irrigation engineer Li Bing investigated the problem thoroughly. He led a team     4     (construct) a levee(堤坝) to redirect a part of the river’s flow. Then they cut     5     channel through Mount Yulei to let the water flow through it. After the system was finished , no more floods     6     (occur). What’s more, it made Sichuan one of the most productive agricultural     7     (region) in China because the redirected water from the Min River could be used for irrigation. If you visit Dujiangyan, you will see an     8    (usual) construction that looks like a fish’s mouth. This famous attraction, Yuzui, together with two other important parts, namely, Feishayan and Baopingkou, was     9     (scientific) designed to control the water flow throughout the year.

    10     (recognize) as a UNESCO heritage site, Dujiangyan has irrigated farms while preventing floods for over 2,000 years.

Starbucks will eliminate plastic    1    (straw) from its stores worldwide in 2021 to reduce pollution    2    (cause) by plastic, the company says. The coffee retailer (零售商) will gradually reduce using single-use straws    3    its more than 28, 000 locations, cutting out    4    estimated 1 billion straws each year. Customers will instead be given plastic lids designed for use without a straw or with non-plastic straws. “Not using a straw is the     5    (effective) thing we have ever done for the environment,” said Colleen Chapman, vice-president of Starbucks’ global social impact, in a statement. The announcement came just one week after Seattle, Washington — home to Starbucks’ headquarters — became the first major US city    6    (ban) single-use plastic straws in bars and restaurants.

Starbucks’ pushback against plastic has drawn a mixed    7    (react). M. Sanjayan, CEO of Conservation International, issued a statement saying “500m plastic straws    8    (throw) away every day in the US” and praised Starbucks for its “meaningful action to protect our oceans” . But many consumers    9    (voice) concern for disabled people. “What about those    10    rely on straws due to disability? I often can’t drink or eat without them.” a customer tweeted.