There are many kinds of trees. All trees have roots. The roots hold trees in the ground. The roots soak up ( 吸收 ) water and food. Then trees get water and food from the roots. You can't see inside a tree. But you can study how water moves through trees.

    First, get a stalk ( 茎 ) of celery ( 芹菜 ) and cut off its end. Put red colour in a cup of water. Then put the stalk of the celery into the red water. Then we can see the red water moving up in the celery easily.

    After half an hour, take the celery out. Cut it in half. Your celery should be red. This is because the water moved up the stalk. Water moves through trees in the same way as it moved through the celery.

    Did you hear the song called Heartbeat? It's very {#blank#}1{#/blank#} in the world. Zade Dirani released (发布) this song {#blank#}2{#/blank#} March 15^th 2018 to remember the seven years of war (战争) in Syria. In the song, one of the {#blank#}3{#/blank#} is Ansam. She is a ten-year-old girl. When she was born (出生), she couldn't see {#blank#}4{#/blank#}. But later people found she could sing very well. She sang the song Heartbeat with another 40 children. They all lost their parents in the war. In this song, children hope (希望) they can have a happy {#blank#}5{#/blank#} and there is no war in Syria. But many people lost their homes {#blank#}6{#/blank#} the war broke out (爆发) on April 13^th 2018 again. Everybody hopes the war can {#blank#}7{#/blank#}. We hope all the kids have food to eat. They can live with their parents. They can study in the classroom. They can sing under the trees and swim in the sea.

    We are lucky to live in a great {#blank#}8{#/blank#}, China. Now we have food to eat. We are {#blank#}9{#/blank#} in the classroom. We {#blank#}10{#/blank#} reading books in the library. So we should study hard and love our parents and friends.

There are many colors in nature. But do you think that a color has weight? Let's do a test.

First, put two objects with the {#blank#}1{#/blank#} weight into two boxes. Then cover the boxes. Third, wrap (包裹) one box with a red piece of paper, the other with white. Now hold the boxes {#blank#}2{#/blank#} your hand one by one. Which one is {#blank#}3{#/blank#} ? It is certain that you will think the red one is heavier. Why do you think so? A scientist did many {#blank#}4{#/blank#} and found that different colors have different weights in a man's mind.

Also, scientists say that people accept the colors they like, and {#blank#}5{#/blank#} the colors they hate. So your body and mind will be {#blank#}6{#/blank#} by using the colors you like. Or you'll be nervous {#blank#}7{#/blank#} even get ill. For example, you {#blank#}8{#/blank#} blue and hate red. If you stay in a room with red windows and wallpaper for two hours, you'll feel you have been there for {#blank#}9{#/blank#} hours. But if the room is blue, you'll feel you have been there for only an hour, And, if a person walks {#blank#}10{#/blank#} of a blue room and into a red room, his temperature will rise. That means our body temperature will change with different colors.

Chopsticks are a pair of small equal-length sticks, usually made of wood, used for eating Asian food. Chopsticks are mainly used in China. And it is believed that the first chopsticks were developed in China. Chopsticks play an important role in Chinese food culture. Chinese chopsticks are usually 9 to 10 inches long. They are round on the eating end which means heaven (天), and the other end is square which means earth. The appearance of chopsticks said goodbye to those days when our Chinese ancestors(祖先)had to use their hands to eat.      

Besides, the use of chopsticks has also been a part of Chinese food culture. There are some taboos that you must pay great attention to when you use chopsticks. Firstly, don't use them to hit your bowl or plate. Secondly, never use them to point at others. Thirdly, don't put them in different food without taking something. Fourthly, don't cross the chopsticks on the table. And lastly, don't leave your chopsticks standing in the rice. Chinese people do this only when they honor (尊重) the dead.

Nowadays, chopsticks have many new usages. For example, you can buy a pair as a gift to your friends and relatives. In Chinese, it reads "筷子", which means having sons soon, so a newly-married couple will be very happy to accept it as their wedding gift.

Doorbells are the bells (铃) for people to ring at a door. When someone hears it, he or she can open the door. Do you know that you can ring a doorbell for fish, too? 

Every spring, millions of fish migrate (洄游) along the river in the city to find better places to lay eggs. But in the river, there are many locks (水闸). They stop fish from swimming through. Weerd Lock is in Utrecht, the fourth largest city in the Netherlands (荷兰). When fish get there, they have to wait a long time before the lock opens for boats to pass through. The lock keeper there is glad to open the lock for fish, but he cannot tell when fish want to get through. So in 2021, Mark van Heukelum, a scientist, came up with a good idea to help solve this problem—by using the fish doorbell. 

Under the water near the lock, there's a camera. People from around the world can visit a website (网站) to see fish through the camera. When you see a group of fish waiting, you can ring the doorbell on the screen. And when the lock keeper notices it, he will open the lock for the fish. 

In its first spring season in 2021, people around the world rang the fish doorbell more than 100,000 times. If you want to join them to help fish, visit the website and ring the fish doorbell next spring. 

In the eyes of many foreigners, Chinese are the best hosts and the worst guests in the world. They're not really bad guests but because the guest-host relationship in China is much different than in some Western countries it appears they are not nice guests. And Western guests sometimes look rude in the eyes of Chinese guests.  

　　In China guests are almost like gods. Whenever I enter a Chinese person's home there is always fruit on the table for me and someone is quick to bring me a cup of tea or water. In the West generally the guest is not a god. Acting according to the host's way of doing things is usual behaviour for a guest. 

　　My wife's mother is a very kind elderly Chinese lady who doesn't smoke. When I see some of her guests smoking in her house, as a non-smoker I feel unhappy. Usually I want to stop them directly but I must realize that she must not do that. In most North America homes if you are a guest and the hosts are not smokers, you should not smoke in their house. At the very least you could ask "Is it OK if I smoke?" But don't be surprised if they say "No, you can't smoke." In our culture if you smoke in their home you are a bad guest, but if they don't allow you to smoke in their house they are not a rude guest.

　　Guests in China also have special habits. Some Western people may not adapt to these habits very soon. Thankfully my wife is Chinese so whenever we visit a Chinese family she tells me to buy them a gift. However giving a gift to a host is not always necessary in my country. So if you invite international guests to your home don't be too surprised if they don't bring you a gift. 

　　In China you probably won't need to change the guest-host relationship very much because you will probably only be the host and Chinese are naturally very good hosts. If Western hosts invite you to their house, try not to be too surprised if their style of treating you is not what you have expected.