Nowadays, more and more people have chances to travel, study, work or even live abroad. It is necessary for you to keep in mind these general    1    （rule） for polite behaviour.

If you    2    （invite）to an American friend’s home for dinner, first of all, arrive on time（but not early）. When you’re invited to someone’s home for a meal,    3    is polite to bring a small gift. Flowers or candies are always appropriate. If you have an attractive item    4    （make）in your native country, your host or hostess would certainly enjoy receiving that as a gift.

    5    （wear） proper clothes and a beautiful smile is simply not enough. Table manners are also of great    6    （important）. Do not open your mouth to talk, unless you have swallowed your food. Also chew food with your mouth    7    （close）. When you want to get the food that is at a distance, do not stretch your hands to reach    8    it. Instead, ask for the food to be passed to you.

Don’t leave    9    （immediate ） after dinner, but don't overstay your welcome, either. When your friends seem to be getting tired and running out of conversation, take their behaviour as a signal to leave. The next day, call or write    10    thank-you note to say how much you enjoyed the evening.

It is in your daily life that you always get into a situation     1     your parents control hundreds of things for you when you are     2     kid, such as the clothes you wear, the food you eat, where you go and whatever can keep you     3    (comfort). It is a good thing. Kids need this kind of protection and help because they are not old enough to take care of     4    (they) and make decisions     5    (correct). But with you growing older, the part of being a teen is developing your own identity, which is different     6     parents’. Different attitudes towards events like parties may lead to     7    (argument), because your parents will always be concerned about you and keep you safe, no matter how old you are. As a result, your parents felt it hard     8     (get) used to the new situation without     9     (know) your latest news. What kids should keep in mind is that in most cases, your parents can understand what you are going through because they     10     (be) teens once.

The Silk Road is in fact a relatively recent term.These ancient roads had no particular name until in the mid­nineteenth century; Baron Ferdinand von Richthofen     1    (name) the trade and communication network the Silk Road. Since then the term     2    (accept) globally.

In the nineteenth century, a new type of travelers stepped onto the Silk Road: archaeologists and geographers, enthusiastic explorers who were eager     3    (look) for adventure.Researchers who came from many countries traveled through the Taklamakan Desert,    4     is now in Xinjiang, to explore ancient sites along the Silk Road,    5    (lead) to many discoveries and studies, and most of all, a renewed interest     6    the history of these routes.

Today，many historic     7    (build) and monuments still stand, marking the passage of the Silk Road through hotels, ports and cities. What’s more, the long­standing legacy (遗产) of this remarkable network is reflected in     8     large number of cultures, languages, customs and religions that have developed for many years along these routes. The passage of merchants and travelers of many     9    (difference) nationalities resulted not only in commercial exchange, but in a widespread and continual process of cultural interaction.    10    (obvious), it has become a driving force in the formation (形成) of diverse societies.

Forgetfulness can be     1     problem both in study and daily life. That is why people use tools like flashcards, puzzles and brain twister games-to force their brains     2     (save) more information.

But, according to a recent study     3    (publish) in the journal Neuron, forgetting has its own uses. Forgetting things improves the efficiency of memory and     4     (help) us to make better decisions.

The point of memory,     5     is known to us, is “to hold on to valuable information”. That’s because our brain has only a limited capacity (容量) to store the information we input. If we try to remember everything     6    (accurate), some useful things will be missed.

What’s more, sometimes too many     7     (detail) can cause mental chaos (混乱) and stop us from     8     (make) the right decision.

If you’re trying to learn the world and “your brain is constantly bringing up many conflicting memories,” said a Canadian     9     (science) in neurology (神经学) called Blake Richards in a news conference, “that makes     10     harder for you to make the right decision.”

9 . When you think of the Arctic, you imagine an icy land of pure white snow, which is considered to be the last really clean place     1    (leave) on Earth. Yet plastic trash has now reached the remote regions of the Arctic and the Alps. A team of     2    (scientist) has discovered large quantities of microplastics(微塑料) — very small pieces of plastic waste — in the Arctic snow. While microplastics have been found in sea-water, drinking water, and even in animals over     3     past several years, this is the first study to show microplastics in snow,     4     indicates it is an airborne pollutant that must be paid attention to.

The researchers state that microplastics in snow suggest that microplastics may be in the air that we     5    (breath). Therefore, it is really important     6    (assess) if microplastics also reach lung tissues.

Previous research has found that they flow over long distances and into our oceans,     7    (damage) ecosystems along the way. They start in our wastewater, when we wash clothes     8     plastic fibers. The wastewater then flows into rivers and out to sea, where they     9    (eat) by sea animals. If people then eat these animals, it means that we’re     10    (probable) eating the plastic as well.

As the first domestic soy sauce (酱油) factory in Cuba has     1     (begin) to produce Chinese-style soy sauce, the history of such products being imported by the island may soon come to an end.

The factory is part of a project     2     (support) by the Chinese Association Min Chih Tang in the     3     (center) province of Ciego de Avila, located some 400 km east of the Cuban capital Havana.

The project is headed by Mey Ru Chen,     4     34-year-old Chinese woman     5     came to Cuba in 2006 to study tourism. “This is another way to promote Chinese culture. It is     6     (actual) a project whose outcome will highly benefit Cuba, as all soy sauce consumed on the island     7     (import) mainly from Europe. It will help the country reduce imports,” she said.

Her     8     (product) are well accepted by locals, Chen said. “Cubans love soy sauce or ‘Chinese sauce’ as they also call it here. It is used to dress a wide variety of dishes; that is why it is so popular     9     the people of Ciego de Avila.”

“We     10     (receive) high quality training in China two years ago. Our main interest at the moment is to diversify our production in the factory and to continue to foster our traditions,” Morgado, Chen’s husband, said.