Grammar is the system of a language. People sometimes describe grammar as the “rules” of a language; but in fact no language has rules. If we use the word “rules”, we suggest that somebody created the rules first and then spoke the language, like a new game. But languages did not start like that. Languages started by people making sounds which evolved (逐渐发展成) into words, phrases and sentences. No commonly-spoken language is fixed. All languages change over time. What we call “grammar” is simply a reflection (反映) of a language at a particular time.

    Do we need to study grammar to learn a language? The short answer is “no”. Very many people in the world speak their own, native language without having studied its grammar. Children start to speak before they even know the word“grammar”. But if you are serious about learning a foreign language, the long answer is “yes, grammar can help you to learn a language more quickly and more efficiently.” It's important to think of grammar as something that can help you, like a friend. When you understand the grammar (or system) of a language, you can understand many things yourself, without having to ask a teacher or look in a book.

So think of grammar as something good, something positive, something that you can use to find your way—like a signpost(路标) or a map.

    Except invented languages like Esperanto（世界语）. And if Esperanto were widely spoken, its rules would soon be very different.

    Mark is always engaged in his work. But this time he felt that it was time for him to take part in his community, so he went to the neighborhood meeting after work. The area city council woman was leading a discussion about how the quality of life was on the decline. The neighborhood faced many problems. Mark looked at the charts taped to the walls. There were charts for parking problems, crime, and for problems in empty buildings. Mark read from the charts, “Police patrols cut back, illegal parking up 20%”. People were supposed to suggest solutions to the council woman. It was too much for Mark. “The problems are too big”, he thought. He turned to the man next to him and said, “I think this is a waste of my time. Nothing I can do would make a difference here.”

    As he neared the bus stop on his way home, Mark saw a woman carrying a grocery bag, and a baby. As Mark got closer, her other child, a little boy, suddenly ran into the street. The woman tried to reach for him, but as she moved, her bag shifted, and groceries started to fall out. Mark ran to take the boy's arm and led him back to his mother. “You gotta stay with mom,” he said. Then he picked up the stray groceries while and the woman smiled in relief. “Thanks,” she said, “You've got great timing.” “Just being neighborly,” Mark said. As he rode home, he glanced at the walls of bus. On one of them was “Small acts of kindness add up.” Mark smiled and thought, “Maybe that's a good place to start.”

    American and British people use different greetings. In the USA the commonest greeting is “Hi”. In Britain it is “Hello!” or “How are you?”. “Hi!” is creeping(不知不觉地进入) into British, too. When they are introduced to someone, the Americans say, “Glad to know you.” The British say, “How do you do?” or “Pleased to meet you.” When Americans say “Good-bye”, they nearly always add, “Have a good day.” or “Have a good trip.” etc. to friends and strangers alike. Britains are already beginning to use “Have a good day.”

    The British usually use “got” in the sense of “have”. The Americans hardly ever do.

AmE: Do you have a car, room, etc.? Yes, I do.

BrE: Have you got a car, room, etc.? Yes, I have.

    There are a number of differences between American and British English in the spelling of words, e.g. check(US)/cheque (UK). Many American words ending in “or”, e.g. honor, labor are spelt in British English with an “our,” e.g. honour, labour. Many verbs in American English with “ize” or “izing” forms, e.g. organize, realizing are spelt in BrE with “ise” or “ising”, e.g. organise, realising. In American English, “practice” is used both for the verb and noun. In BrE, the verb is spelt “practise”, and the noun “practice.” In American English, one writes “traveler,” while in British English, one writes  “traveller”.

    It was once predicted that British and American English would become separate languages finally. But the opposite has happened. The links(联系) between the two countries are so strong that linguistically(语言上地),and probably culturally(文化上地) too, they are closer together than ever.

    Darwin noted that some human emotional expressions might have started as part of a physiological function: for example, exposing the teeth to bite food. The function, however, took on meaning and became a form of communication which signals anger.

    The same may be true for the animals. Baby monkeys cry for attention. They also cry to signal to an adult that they want to be carried.

    “Chimpanzees do make upset voice when they are being weaned (断奶) by their mothers or have lost their mothers or another individual,” says Anne Pusey, a professor at the University of Minnesota. “They whimper (呜咽) and cry and scream. When we hear these calls, the emotion involved seems obvious. However, they do not weep in the sense of producing tears. I have seen an adolescent male whimpering when he lost sight of his older brother with whom he had been traveling.”

    Babies of many mammalian species, including rats, cry. Moreover, when a baby rat cries, often his mother brings the fallen pup back into the nest. This is probably a straightforward communication, as it is with humans. However, psychologists at the University of Iowa aren't convinced.

    The Iowan researchers can cause the same crying sounds by producing large decreases and then increases in blood flow. The blood flow also goes down when baby rats get cold. Thus, they conclude baby rats cry in the same way that we sneeze. Of course the rat baby could be crying because he's cold and wants his mother to know.

    “All young mammals make cries when separated from their mother,” says Jaak Panksepp, a psychologist at Bowling Green State University. “If you're willing to call this crying, then certainly other animals show this emotional response.” he says, “Some of us take seriously that animals do have emotions.”

Plastic-Eating Worms

    Humans produce more than 300 million tons of plastic every year. Almost half of that winds up in landfills(垃圾填埋场) and up to 12 million tons pollute the oceans. So far there is no effective way to get rid of it, but a new study suggests an answer may lie in the stomachs of some hungry worms.

    Researchers in Spain and England recently found that the worms of the greater wax moth can break down polyethylene, which accounts for 40% of plastics. The team left 100 wax worms on a commercial polyethylene shopping bag for 12 hours, and the worms consumed and broke down about 92 milligrams, or almost 3% of it. To confirm that the worms' chewing alone was not responsible for the polyethylene breakdown, the researchers made some worms into paste(糊状物)and applied it to plastic films. 14 hours later the films had lost 13% of their mass — apparently broken down by enzymes (酶) from the worms' stomachs. Their findings were published in Cun ent Biology in 2017.

    Federica Bcrtocchini, co-author of the study, says the worms' ability to break down their everyday food — beeswax — also allows them to break down plastic. "Wax is a complex mixture, but the basic bond in polyethylene, the carbon-carbon bond, is there as well," she explains, "The wax worm evolved a method or system to break this bond."

    Jennifer DeBruyn, a microbiologist at the University of Tennessee, who was not involved in the study, says it is not surprising that such worms can break down polyethylene. But compared with previous studies, she finds the speed of breaking down in this one exciting. The next step, DeBruyn says, will be to identify the cause of the breakdown. Is it an enzyme produced by the worm itself or by its gut microbes(肠道微生物)?

    Bertocchini agrees and hopes her team's findings might one day help employ the enzyme to break down plastics in landfills. But she expects using the chemical in some kind of industrial process — not simply "millions of worms thrown on top of the plastic."

Courage is a quality that everyone has, but it sometimes disappears because of bad experiences or memories.{#blank#}1{#/blank#}So, how can people build courage? By identifying the source of any lack of courage and actively changing your behaviour, you can build courage. 

Determine your specific fears. People are often unwilling to admit that they are afraid of something. In order to begin building courage, you need to determine your specific fears.{#blank#}2{#/blank#}This may help you to work out a plan to overcome them and build your courage. 

Recognize your courage. Just as it's important to identify your fears, you should also recognize that you also have courage in many situations. {#blank#}3{#/blank#}It can help you to figure out how to apply this quality to situations that cause fear. It can also help develop your behaviour and build courage.

Develop a practical plan to build your courage. Once you've identified your specific fears and recognized situations where you exhibit courage, make your plan to build your courage and update it when necessary. {#blank#}4{#/blank#}The reason for that is it helps you be on track if you have difficulties and see your progress over time.

Avoid comparing yourself with others. Every person is different and comparing yourself with other people can minimize your self-confidence. Focusing on yourself is essential to building your confidence and courage.

 {#blank#}5{#/blank#}Two characteristics of courageous people are that they not only have confidence, but also they believe in their ability to succeed and overcome fears. By developing and projecting confidence in yourself, you set yourself on the path to building and maintaining courage. 

A. Part of building your courage is taking risks.

B. Embrace the positive and avoid the negative.

C. Make a list of your fears as you figure them out.

D. Having a clear strategy you can follow is important.

E. Take the time to acknowledge that you are courageous.

F. Have confidence and believe in your ability to be courageous.

G. Showing courage is necessary to succeed in many situations in life.