Reuters reported that the scientist’s efforts got rewarded when the twin chickens were cloned in the lab after years of experiments. This breakthrough    1    (possible) enabled people’s adored pets to bring to life.    2    , it bothered him from time to time that the chickens, health was in poor condition because they were     3    (able) to resist illnesses. This drawback    4    (cast) him down. Merely two weeks later, the clones and their carrier died,    5    struck frustration into his heart. He retired before he attained his ambition and became a member of an opera chorus to relieve his depression.

Shortly afterwards, the media published a conservative    6    (argue) objecting to cloning owing to moral problems, and suggested commercial profits from cloning    7    (forbid).

When    8    (interview), the scientist stared at the decorations on the ceiling, thinking for a while, and then said, “I’m not in favour    9    any arbitrary assumptions, but    10    (undertake) cloning does differ from the straightforward procedure of making loafs out of flour. Until we accumulate enough exact knowledge, any practice is in vain and is bound to fail.”

An eastern bluebird sits on a branch, patiently watching the ground below. Suddenly, it spots a beetle. The bird spreads     1     blue wings, flies to the ground, and quickly eats the small insect. Then the     2     (color) bird returns to the branch     3     (wait) for its next snack.

Eastern bluebirds can     4     (find) in the eastern parts of North and Central America. The eastern bluebird is the state bird of New York and Missouri. These birds can often be seen in trees or on fences, looking at the clearings (空地) and searching     5     food.

These birds are skilled    6     (flier) with incredible vision. They can spot       7     insect on the ground from 60 feet away. Eastern bluebirds often sing,     8     (use) their voices to stay in touch with other members. They also use sounds to warn enemies to stay away from their small, cup-like nests    9     are usually built inside old woodpecker holes. Most baby eastern bluebirds     10     (simple) leave the nest about three weeks after they hatch out (孵化), but some stay to help their parents with the next batch of eggs.

3 . Around the end of the first century AD, a Roman writer called Pliny wrote about a terrible volcanic eruption that he     1    (witness) as a young man. The eruption had occurred on August 24th, 79 AD. The tragedy left     2     deep impression on Pliny     3     had lost an uncle in the eruption. However, more than 1,600 years later, some     4    (science) found that the lost towns had been buried under the ash of Mount Vesuvius. Pompeii is like a “time capsule”     5    (preserve) a frozen moment in history.     6     the eruption occurred,     7     had been a booming Roman city with temples, markets, restaurants and theaters. Today you can visit these buildings by walking along the     8    (origin) streets of the city. And     9    (many) than 250 years since excavations started, thousands of tourists and hundreds of scientists visit Pompeii every year     10    (learn) more about the ancient world.

According to a recent American study, food allergies (过敏) are becoming more and more common,     1     (particular) among children. About 8% of those under 19 have developed an allergy. That means     2     total of 6 million children suffer from allergies in the USA.

The foods that are mostly responsible for such allergies     3     (be) milk, eggs, peanuts, fish, nuts and wheat. But why are food allergies increasing? Experts give the     4     (reason). One is that everything is too clean. Our body does not have the training     5     (fight) off attackers. Besides, genetic (基因的) engineering has changed most of the food we eat today.

Although a food allergy can begin     6     any age, most allergies start in childhood. Some allergies go away when you grow up, like milk or egg allergies. Others, like fish or nut allergies, are probably with people in     7     (they) whole life.

In fact, at least one third of the children     8     (affect) are allergic to more than one kind of food. They have trouble staying     9     (health) and getting the right diet. Therefore, parents     10     children have allergies should always have some drugs with them. These drugs act quickly and let children breathe better.

My name is Marly. I'm from an Inuit village in the far north of Canada. Our lives are closely connected     1     the natural world of the Arctic.

Though we live in     2    (regularly) houses, we stay in temporary shelters called "igloos" when we go hunting. Igloos are made of snow or ice. On the one hand, they are quite warm inside and building materials can     3    (find) everywhere. But on the other, they can only be kept for around fifty days.

We get our food from the nearby sea. Eating a lot of fish and meat    4    (keep) our bodies strong so that we can fight the cold. But the downside is that the cold weather makes it difficult     5     us to grow enough vegetables and fruit.

It's    6    (absolute) dark here for three months of the year,     7     is the period called "the polar night". So, life can sometimes be boring! But the good thing is, during that time the elders tell us stories about our people. It gives us more time     8    (stay) with our family and friends.

Nowadays, ships bring tourists to the Arctic. The advantage to this is that it brings more money and job    9    (opportunity). But the disadvantage is that our environment is being polluted.

But one thing is for sure: no matter how things change, our traditions will remain     10     important part of our lives.

Riding a bike or a motorbike in cities can be dangerous. You must pay attention to your own     1     (safe) when you’re riding your way through city streets.

According to a report, 65% of car accidents m 2017     2     (relate) to bicycles and motorbikes in China. It was also worth     3     (mention) that these accidents mostly happened on the main roads rather than in other areas, such as sidewalks or bicycle paths. It showed that people lacked awareness especially     4     they were sharing roads with cars and trucks.

A large number of bicycles, motorbikes, and cars pour into the streets every day.       5     (reduce) those painful accidents, you should know the local traffic rules and stay on your path. Watch the traffic lights ahead     6     (close) and do remember to ride     7     the flow of traffic, not against it.

It’s also important for a rider to protect the head. Regardless of your age and your riding speed, you should always prepare     8     (you) for a safe ride. According to the experts, there is no     9     (good) choice to protect yourself than wearing a suitable helmet (头盔).

Keep the above     10     (suggest) in mind and wish you a pleasant trip on the road.

It was one busy morning in those rush hours when I hopped into the bus heading town to run some errands.

I sat next to some guy     1     name was Musa. He said hi and I replied     2     a smile and our conversation began from there. We talked about a lot of things     3     (particular) about life and work and he just started complementing(称赞)my natural look. He said he     4     (impress) with how natural I was, for he had merely met a girl     5     (wear) no makeup at all.   

Musa said those words genuinely and like any girl, I     6     (feel) good and appreciated it even though it was from a     7     (strange). In the back of my mind I thought he would then ask for my number as most guys did but,     8     (surprise), he said goodbye to me at the terminal and left. I have never seen him since then.   

    9     I am trying to say here is that sometimes people are different from what they are thought of by the society, so keep     10     (see)the best in people instead of assuming they do things with bad purposes.

After a snowfall, the air is fresh. However magical it looks, snow and ice must    1     (remove) from driveways, roads and sidewalks. Uen you reach for a de-icer to clean off your front steps, find something safe and clean. There are many friendly ways     2     (keep) the ice away.

When winter comes, many people put bags of road salt at home. Yet many do not know that when the salt melts (融化), the runoff ends up     3     rivers and lakes. It harms the water. Chloride (氯化物) can be     4     (danger) to children who play in the snow.

It is time to use “smart salt”. Thd good news     5     (be) that there are many healthy choices. Eco-friendly options include    6     (use) kitty litter or sandbox sand. These will not melt the ice but will offer traction (摩擦力) to reduce the danger of slipping on the ice. There is also     7     effective DIY method: using. dish soap mixed with alcohol.

Many countries are becoming more aware of the environmental dangers of de-icing materials now. Some cities are spreading less salt on the roads, while others are adding sugar,     8     makes melting more effective. This is     9     (clear) a path in the right direction. You can make a     10     (different) by starting right on your front doorstep!

When an animal species is considered endangered, it means that the International Union for Conservation of Nature (IUCN) has evaluated it as nearly extinct. It means that it is dying out and the rate of birth is     1     (low) than the species’ death rate. Today, more and more animal and plant species are close to extinction because of a     2     (vary) of factors that cause a species     3     (become) endangered, and as you might expect, humans play     4     role in quite a few of them.

    5     (fortunate), many people around the world are devoted to     6     (help) these endangered animals through many efforts, including prohibiting illegal poaching, stopping pollution and habitat destruction. So far, many countries     7     (pass) laws banning specific exotic (外来的) species known to endanger native habitats from   entering the country. Exotic species are sometimes referred to as invasive (入侵性的) species, especially in cases of banning them.     8     instance, the United Kingdom has placed raccoons and cabbages on their invasive species list, all of     9     are barred from entering the country. Furthermore, poachers have developed     10     (technique) for selling animals. Baby bears and monkeys have been put into suitcases for transport. Live   animals have been sold to people who want exotic pets or medical research subjects.

Michaela Bercu likes to break down barriers. In November, 1988, she became the first model     1     (wear) jeans on the cover of Vogue, an unusual formality of the high-end fashion magazine.

It’s now 30 years later, and Bercu is hoping to make another change: breaking the barriers of entry to volunteering.     2     (inspire) by the word “contribute”, she has developed Tribu,     3     connects needs with those who are     4     (will) to help. She has spent the past four years     5     (develop) the platform with her husband.

Bercu firmly believes that volunteering does     6     (much) for the giver than the one who receives the kindness. She said,“So much research has been done with people of all ages and it shows that volunteering makes you feel wonderful. The experience of bringing someone a smile on their faces gives you so much     7     (satisfy).”

The app has expanded across Israel and has become particularly popular with high school students there, as they     8     (require) to do a certain number of hours of community service     9     they can graduate.

Bercu is hoping that the movement she started will continue to expand. “In five years, I would love the app to be in every household around the world because we can give and get so much from     10    .”