When you read a book, you are likely     1    (notice) that a brand new book has a rather special smell,     2    differs from that of an older book. Where does it come from? The answer is simple—the paper, the ink and the glue.

Around 200 AD, the Chinese first came up with paper, one of the greatest     3    (invent) in the world. It is made from wood. The wood must be processed with various chemicals     4    (add) to change its structure, to remove acid and to whiten the paper. Then comes the ink—there are many kinds. Some fade with time,     5     others get darker than years ago. Finally, different glues     6    (use) to join the sheets together and attach the covers, whether hardcover     7     paperback. Therefore, you can smell different chemicals coming out of your new book.

Today, the forms of books     8    (change) greatly ever since the birth of eBooks. They might be     9    (convenience), but you can't give your copy to others     10     a present, and they don't smell as nice.

Believe it or not, challenging some of your limits, which you have never tried,     1     (help) you change for the better. When meeting with difficulties or new things, don’t step back. Rather, figure out     2     you are frightened of and do it     3     (continuous).

If you are a salesman, afraid of talking to people personally or over the phone, now, instead of     4       (feel) scared and concerned about your failure, spend at least five minutes a day to pick up the phone and make a call. Although someone may hang up on you, don’t stop on     5     first try! Eventually, you can look at fear in the eyes, saying, “Go on, and I am not scared!” Your confidence will increase significantly in this way.

Recent     6       (survey) show that starting with a hobby also encourages us to face challenges, like cooking, sewing, gardening, painting and so on. Whatever it is,     7     (believe) it is a good chance to try new things. And these hobbies may also give you some extra income, if     8       (carry) out well.

    9     is no denying that many other ways can also help you accept challenges, like setting aside fixed time to exercise and travelling with friends or alone. All in all, challenging yourself can make you     10     (brave) and adapt to society better.

I gave one of my favorite sun hats recently to a friend Jack who had been looking for one like mine for several     1     (week). I found it online and had it sent to him for his birthday.

Later, I     2     (lose)my own and I was upset! That hat had traveled everywhere with me. But then a     3     (difference) friend came back from his trip to the Philippines.     4     did he give me as a gift? A sun hat!

I want to host my friends and cook a dinner for the large group this week.     5     (fortunate), I have the chance to cook for a large group of people in my life. I enjoy     6     (learn) a few new recipes (食谱) on my own, shopping for the food, and cooking for them. Just today, I hiked with Jack and when we said goodbye, he took a box of food out and he wanted me     7     (have) them. There were all kinds of potatoes, onions, pears, apples and peaches. Those foods can be ready for the large group of my friends. Jack didn’t attend my party nor did he know about     8     dinner this week, and he didn’t do it     9     purpose. What an unexpected thing! Since then, Jack and I have been     10     (close) than ever.

Earth Day     1     (found) in 1970 as a day of education about environmental problems, and Earth Day 2020 occurs on Wednesday, April 22 — the holiday's 50th anniversary. The holiday is now a global     2     (celebrate) that's sometimes extended into Earth Week, a full seven days of     3     (event) focused on green living.

    4     (elect) to the U.S. Senate (参议院) in 1962, Senator Gaylord Nelson was determined to convince the federal government that the planet was     5     risk. In 1969, Nelson developed the idea for Earth Day after     6     (inspire) by the anti-Vietnam War "teach-ins" that were taking place on college campuses around the United States.

Denis Hayes, a young activist     7     had served as student president at Stanford University, was selected as Earth Day’s national coordinator (协调者), and he worked with     8     army of student volunteers and several staff members from Nelson's Senate office     9     (organize) the project.

The first Earth Day was effective at raising awareness about environmental problems and transforming public attitudes. Earth Day kicked off the "Environmental decade with a bang," as Senator Nelson later put it. The theme of Earth Day 2020 is "climate action." Earth Day. org hopes it will be the     10     (large) volunteer event in history.

In 1991, Beijing musician Wang Wei went on a tour, when he became fascinated by the shakuhachi, a kind of Japanese bamboo flute (笛子). Later, he found out that the shakuhachi,     1     was called chi ba in Chinese, was introduced to Japan during the Tang Dynasty (618—907).

    2     (astonish) and ashamed of how he was ignorant of the country’s rich musical tradition as a     3     (profession) musician, Wang started learning and researching on Chinese musical instruments made of bamboo. He has found that among the 90 wind instruments     4    (identify) by the Chinese Music Dictionary, 47 are made of bamboo.

During the past three     5    (decade), the talented musician traveled around the country       6     (find) the finest materials for making bamboo instruments. The small balcony at his home in Beijing has become his studio     7     instrument making.

He also gathered a group of musicians to form the country’s first bamboo orchestra. While     8     (realize) his expectation, Wang is also proud that the orchestra’s birth and development are also an effort of protecting the environment. Bamboo is among     9     fastest growing plants on earth, gaining 1.2 meters every day under appropriate conditions. Since 2002, the State Forestry Administration     10     (try) to replace the use of wood with bamboo to protect the environment.