There are 115 distinct (独特的) species of pine trees with 35 native to North America. Pines are defined as evergreens with long, needle-like leaves and are only native to the northern hemisphere. Pine trees are an adaptable and tough species that can survive in many conditions where other plants cannot. The average pine tree is 45 to 60 feet tall, but some are nearly twice as high.

Western White Pine

    The western white pine grows the tallest of any pine tree, reaching up to 110 feet in height. They have blue-green needles arranged in bundles (束) of five and produce a long cone (球果).

Bristlecone Pine

    The bristlecone pine grows slowly, reaching about 20 feet tall. It is one of the oldest species of pine.

Mexican Pine

    The Mexican pine can grow to 50 feet tall, with long, slender needles that drape (下垂) off it like a weeping willow (柳树). Often nicknamed the “willow pine”, it is native to Mexico. Its leaves can droop up to 12 inches long.

Sugar Pine

    The sugar pine is another of the large pine species, such as the bull pine, but it also has the largest cones of any pine species, at 10 to 20 inches long. It grows from Oregon to California and is often used for construction.

Jack Pine

    The jack pine is one of the smallest species of pine with rare leaves. Compared with the pines mentioned above, it doesn't seem to belong in the family. It is considered a member of the scrub-pine family; it prefers sandy soil.

Paris

Passengers carried per day: 4.4m

Cost of ticket: 80p flat fare

Length: 131 miles    Lines: 14   Stations: 297

    In Paris there are pleasures for those who use the Metro(地铁) — many of them artistic. The graceful Art Nouveau dragon-fly entrances are just the most noticeable on a Metro system which celebrated its 100^th anniversary by spending 30 million francs (£2.9million) on making its stations works of art. On my way home I pass Bonne Nouvelle station in the heart of Paris's cinema district. There, during the cinema festival this summer, special lighting effects dot the platforms and films are projected onto the large advertising boards.

    More than anything the metro is efficient. “When I worked on line 4”, says a retired driver, “we had exactly 30 minutes and 15 seconds to complete the journey. If it took any longer, they cut our pay.” But there are problems. Many Metro stations have too many stairs, and changing lines at big interchanges(交换) can be tiresome.

Moscow

Passengers carried per day: 9m

Cost of ticket: 12p

Length: 164 miles    Lines: 11   Stations: 162

    The first underground passage for the Moscow Metropolitan started in 1932. Three years later the trains started running. They haven't stopped since— every 90 seconds or two minutes during rush hour, every five minutes the rest of the time, from 6 a.m. till 1 a. m. There may be a crowd of people but there is seldom a wait.

    The trains take you through spacious and spotless stations. For tourists it's a major sightseeing attraction: from Russian Art Deco to neo-classical, the Metro stations are not to be missed.

Tokyo

Passengers carried per day: 7m

Cost of ticket: 90p ~ £1.68

Length: 177 miles    Lines: 12   Stations: 209

    Trains do not just arrive on time in Tokyo. They stop right on the platform mark so that passengers can line up knowing exactly where the doors will open. Train driving is a respectful job for life, for which the applicants must pass a strict screening of health checks, interviews and written exams before they can put on the enviable uniform, cap and white gloves.

    However, overcrowding means it is far from perfect. At rush hours, some stations employ part-time platform staff to push in passengers. Carriages can be filled to 184% of capacity(容量). The main reason for such conditions is that the Tokyo subway station system has only 15 miles of track for every 1 million people, compared to 36 on the London Underground. New lines are under construction, but at a cost of £500,000 per meter of rail. Progress has been slow.

Mexico City

Passengers carried per day: 4.2m

Cost of ticket: 11p flat fare

Length: 99 miles    Lines: 11   Stations: 175

    Fast, relatively safe, and very cheap, Mexico City's underground is an ideal place of order and efficiency compared to the disorders above. The Mexican capital's underground system is the biggest in the continent and one of the most subsidized (获得补助的) networks in the world.

    The first trains leave the station at 5 a.m. and the last after midnight as the crowd move from the outskirts of the 20 million-strong megacity (大城市). Mexico City's Metro also attracts a sizeable group of passengers who are unwilling to spend hours in traffic jams. There is a master plan to build new lines and extend existing one, but financial constraints (约束) complicated by the fact that the system runs through different jurisdicitons (管辖权) mean progress is slow.

    When the sun sets in Hong Kong, the city skyline comes alive. Billboard（广告牌）lights flash, and light up the crowded streets. The colorful lights from the tall buildings are one of the city's main attractions.

    “Oh, my god. The lights are so amazing. We love it. It's so nice.” said one visitor.

    But this appreciation is not shared by everyone in Hong Kong. Lat year then government reported a record number of complaints. The curtains may be drawn. But residents argue the bright light outside is hard to escape. “We receive some complaints about the light pollution. They find it very hard to sleep or they have disturbance from the light outside.”

    Scientists at the University of Hong Kong spent 18 months studying levels of light pollution and collecting more than 5 million measurements. They found Hong Kong one of the world's worst “victims”. The lights pollution condition in Hong Kong was extremely severe. Particular in cities, the night sky brightness, as well as the lights, is a few hundred times over the level of that of a night sky without light pollution. In cities such as Seoul, London, Shanghai and Paris, billboard lighting is under control. And there are punishments for people who go against the law.

    But in Hong Kong, there are no laws. A volunteer regulation called Charter of External Light（户外灯光约章）encourages visitors to switch off between 11 p.m. and 7 p.m. The critics say it's not enough to make a difference. The government says 4800 businessmen have signed up to the Charter so far. And it's satisfied that it's working.

    But not everyone is convinced and some residents are taking upon themselves to act. Zoe Chow led a campaign to have a commercial building switch off their midnight. She won but she believes the lights will eventually turn back on. “I know that the building has signed the Charter of External Light. But it is voluntary, not mandatory（强制的）.

    You can't choose friends for your child, but you can help him learn to choose friends wisely. {#blank#}1{#/blank#} Here are a few ways to help your child make friends.

    Build your child's self-confidence.

    When he succeeds or has made a great choice, tell him you are proud of him.{#blank#}2{#/blank#}Your middle school student is going through many changes and may feel like he isn't “good enough”. Building his self-confidence will help him feel more confident and will make it easier for him to form healthy friendships.

    {#blank#}3{#/blank#}

    Give him your full attention when he talks, and really listen to what he has to say.

    Discuss the qualities in a friend with your child.

    Discuss with your child the qualities that matter most, such as being reliable and kind, and making good choices when it comes to avoiding alcohol and cigarettes.

    Get to know your child's friends.

    {#blank#}4{#/blank#} It's more important to talk with them and find out what they like to do. Allow your child to invite his friends over and get to know them better.

    {#blank#}5{#/blank#}

    After-school clubs and sports programs are good places for meeting new people. Be open to exploring different activities with your child to find something that he enjoys.

A. When he does not succeed, help him feel better and keep trying.

B. You can teach him ways to find friends who will have a positive influence on him.

C. There are many types of friends and we should be careful when making our choices.

D. Introduce your child to new groups of people.

E. Friends are very important for us.

F. Talk with your child every day and listen to his concerns.

G. Try not to judge your child's friends according to how they dress.

    Reducing class size has traditionally been seen as an important way to improve a student's educational experience. Many often believe that smaller classes would permit teachers to give more personal attention to their students.{#blank#}1{#/blank#}.

    But one recent study suggests there's not much research-based evidence to support this idea. The research was collected by a team from Denmark's Danish Center for Social Science Research.

The study notes that one of the main problems with reducing class size is that it can have very high costs. {#blank#}2{#/blank#}. Financial limitations make it very difficult for many schools to reduce the number of students in the classroom.

    The new study began by examining 127 studies on classroom size. Its goal was to examine the major research studies already completed on the subject. {#blank#}3{#/blank#}. In the end, the research centered on 10 main studies with possible sampling (采样)problems.

    The researchers concluded that there's some evidence to suggest that reducing class size may lead to some improvement in a student's reading achievement. {#blank#}4{#/blank#}. They found just a 53-percent chance that a randomly selected test score from a student from a small class would be higher than the selected score of a student from a larger class. {#blank#}5{#/blank#}. This led the researchers to conclude that there would be no benefit at all to math students in a smaller class size.

A. But they said the effect is very small

B. For mathematics achievement, the result was 49 percent

C. This can theoretically lead to improved academic results for students

D. Many public opinion studies have shown teachers favor smaller class sizes

E. The effects of larger class size can stay long after the students complete their education

F. Increasing class size is one of the most common ways school systems control education spending

G. They especially centered on those trying to measure if smaller class size led to greater academic success