Welcome to Isle Royale National Park! It is a US national park in the state of Michigan.

    Isle Royale is surrounded by the deep blue waters of Lake Superior, the largest freshwater lake on Earth by area. No cars are permitted in Isle Roy ale. There are no real roads on the island. The only way to get to the park is by boat or sea plane. A boat trip to Isle Royale takes three to five hours. Isle Royale is the largest of the islands within the national park. It is over 72 kilometers long.

    The whole national park covers a total area of 2, 320 square kilometers, with 540 square kilometers above water. Isle Royale became a national park in 1940. But once they arrive, most visitors stay a white. The average stay for visitors in Isle Royale National Park is 3.5 days. Isle Royale offers hiking, camping, boating and even scuba diving.

    Visitors to Isle Royale can see a lot of mouse and wolves in winter. The national park is closed from November l through April 15, due to extreme weather conditions. But for the other months of the year, Isle Royale offers green forests and clear blue waters.

    The unknown world's mystery

    The sea is the biggest unknown part of our world. It covers about seventy-one percent of the earth. There is still much to be discovered about this huge part of water. If the waters of the ocean could be removed, the sea floor with its wide valleys(峡谷), tail mountains and long rivers in the sea would be a special sight.

    Tourism under the deep blue sea

    From tourist submarines(潜艇) to underwater dining, undersea tourism is making a big splash.

    Tourists can now explore(探索) the world under the sea without ever getting wet.

    Tourist submarines

    The popularity of submarine tours has grown fast during these years. Now, submarine tours have been on in more than 20 places worldwide, including the waters around Okinawa and Taiwan's Green Island. The submarines carry nearly 2 million tourists each year. Large windows give passengers special views as the submarines explore colorful coral reefs and sunken ships. Most one-hour tours cost about $ 80.

    Underwater dining

    For a more fantastic experience, tourists can enjoy fine dining under the sea. In 2016 the Hilton Maldives Resort & Spa opened the world's first underwater restaurant, Ithaa. Tourists walk down a staircase into the restaurant, which rests 35 feet in the Indian Ocean. You can have a great ocean view. But this excellent view doesn't come cheap. The dinner costs about $ 400 per person. Be sure to book it early, too, The restaurant seats only 14 people.

    Stonehenge means "hanging stones". They stood in a circle, with 30 more stones lying on top to form a ring of rocks. There was also an inner circle built with similar stones. The stones set up in a trilithon(巨石牌坊) pattern.

    A trilithon is made of two stone pillars with a stab of rock laid across the top. The stones weigh up to 20 tons each. People wonder how the huge rocks were placed that way.

    Historians agree that Stonehenge was built in three different stages. The first stage took place about 5, 000 years ago. At that time, a large circular earth wall was made. Historians believe the wall was dug and cut with tools made form anglers(鹿角) of red deer. The earth wall was about 98m in diameter(直径) a 5-meter-tall stone was placed near the center. Then, they had to transport the large blue stones (up to 4 tons) 384 kilometers to Stonehenge. Experts think they might be moved across ice and snow. The ground in winter in this area is usually full of ice and snow, making it easier to move the rocks. The next task was to stand the stones up. The most difficult task was putting the top stones in place. Each one of these tasks took a lot of planning and a lot of strength, but the workers of Stonehenge were excellent builders.

    Why was the monument built? Some scientists think it's a burial ground. There are over 400 graves (burial sits) nearby. A man was buried with two gold earrings which are the oldest gold ever found in Britain (dated to 2470 BC). Others think Stonehenge was built by early astronomers. Scientists believe that when a person stands in the center of the monument, the changing of seasons can be seen. Certain stones mark the location of the rising and setting moon in midwinter. Other stones mark the rising and setting sun in midsummer. The ancient people held religious ceremonies on these days. These ceremonies probably asked the gods to bring good weather for crops and to protect the people from bad weather.

    Stonehenge is an engineering success. Thousands of years later, it still stands. As a calendar, Stonehenge is very accurate. It shows that early people had a deep understanding of the movements to the sun and the moon. They didn't have machines or computers, but Stonehenge shows people could do many things using only their muscles and their brains.

    More and more teenagers are using the Internet nowadays, but some of them aren't using it in a proper way. If you follow these suggestions, it'll be much (安全的) than you might think.

     Do not give your password to others and never give out your home (地址), real name, age, school or phone number to those (陌生人).

    Do not share your (私密的) information in Moments(朋友圈).

    Never answer unwanted (电子邮件).

    Be (小心的) when you are using public Wi-Fi or scanning QR codes.

    Never go and meet anyone you met online (没有) your parents' permission and never go (单独地).

    Keep a separate credit(信用) card just for (购物) online. This will make it easier to cancel(取消) (如果) something bad happens and your other credit cards can still be used.

A: Hello. Nick! Have you David?

B: No, I haven't. What' wrong?

A: I found a yellow jacket on the playground. I think it is .

B: It can' be his. The jacket is much too small for him.

A: Then it be Bob's. I saw him on the playground just now.

B: But Bob' jacket is black.

A: do you think it could be?

B: Let me have a look. Oh. It must be John's.

A: Why do you think so?

B: Look! I found his school ID card in one of the pockets(口袋).

A: You're right. Let' go and give it to him.

B: OK. He is in the library and books. Let's go.

要求：行文流畅，脉络清晰，字迹工整，80词左右。开头已给出，不计入总词数。

    Whose are these things?