1 . Hundreds of millions have rolled up their sleeves for the COVID-19 vaccine, but why haven’t they rolled up their pants instead? What’s he science behind why we get most vaccines in our arm?

Most vaccines are given in the muscle—this is known as an intramuscular injection (肌肉注射). Some vaccines, are given orally. Others are given just beneath the skin.

But why is he muscle so important, and does location matter?

Muscles make an excellent vaccine administration (药物的施用) site because muscle tissue contains important immune cells Thee immune cells recognize the antigen, a tiny piece of a virus or bacteria introduced by the vaccine that stimulates an immune response. In the case of the COVID-19 vaccine the immune cells in the muscle tissue pick up these antigens(抗原) and present therm to the lymph nodes(淋巴结). Injecting the vaccine into muscle tissue keeps the vaccine localized, allowing immune cells to sound the alarm to other immune cells and get to work. Once a vaccine is recognized by the immune cells in the muscle, these cells carry the antigen to lymph vessels, which transport the antigen-carrying immune cells into the lymph nodes. Lymph nodes, important parts of our immune system, contain more immune cells that recognize the antigens in vaccines and start the immune process of creating antibodies.

Muscle tissue also tends to keep vaccine reactions localized. Injecting a vaccine into the deltoid (三角肌) muscle may result in local inflammation(红肿) or soreness at the injection site. If certain vaccines are injected into fat issue, the chance of irritation (刺激) and inflammation reaction increases because fat tissue has poor blood supply, leading to poor absorption of some vaccine components.

Yet another deciding factor in vaccine administration location is the size of the muscle. Adults and children aged three and older tend to receive vaccines in their upper arm in the deltoid. Younger children receive their vaccines mid-thigh(大腿) because their arm muscles are smaller and less developed.

Another consideration during vaccine administration is convenience and patient acceptability. Can you imagine taking down your pants at a clinic with strangers around? Rolling up your sleeve is much easier and more preferred.

2 . I still cannot forget the story—one story determining my life.

I was sure I was to be killed, even though I was wrongly put in prison. I became terribly ________. I searched my pockets to see if there were any cigarettes, which had ________ their search. ________, I found one but I had no matches.

I looked through the bars at my jailer (狱卒). He did not make ________ contact with me. I called out to him, “Have you got a light?” He came close and ________ the match, his eyes accidentally locked with mine. At that moment, I smiled. I don’t know why I did that.

In any case, I smiled, and my smile leaped through the bars and ________ a smile on his lips, too. He lit my cigarette but stayed near, looking at me directly in the eyes and continuing to smile. I kept smiling at him, now aware of him as a person and not just a(an) ________. And his looking at me seemed to have a new meaning, too.

“Do you have ________?” he asked.

“Yes, here, here.” I took out my wallet and nervously fumbled(胡乱摸找) for the pictures of my family. He, too, took out the pictures of his family and began to ________ his plans and hopes for them. My eyes filled with ________. I said I ________ that I’d never see my family again. Tears came to his eyes, too.

Suddenly, without another word, he ________ my cell (小牢房) and silently led me out.

Out of the jail, quietly and by back routes, out of the town. There, at the edge of town, he ________ me. And without another word, he walked toward the town.

My life was saved by a ________.

Yes, the smile is the unaffected, unplanned, natural connection between people. I really believe that if that part of you and that part of me could ________ each other, we wouldn’t be enemies. We couldn’t have hate or envy or fear.

3 . People are consumers(消费者). We have to spend large parts of our days finding，buying，cooking and eating our food．Did you ever think it might be nice to be able to make your own food like plants do?     1     They perform a process called photosynthesis using light from the sun, water and carbon dioxide. The end result of this chemical reaction is sugar for the plant to “eat”. The plant gives off water and oxygen.

    2     Plants have special structures called chloroplasts(叶绿体) that animals don’t have. These structures are filled with chlorophyll, which gives leafy green plants their green color. Their main job is to absorb light from the sun. Chloroplasts can absorb every color except green. Light makes chlorophyll active. It creates an energy that separates water out into hydrogen and oxygen.    3    

Hydrogen from the water combines with carbon from the carbon dioxide we breathe out. Oxygen is sent out into the air.

    4     Plants rely on the carbon dioxide that we breathe out, and we rely on the oxygen that they “breathe” out. This is one good reason for protecting plant life on Earth. Many plants can produce a constant supply of oxygen for us. We need plants in order to survive.

Conservation(保护) projects around the globe are aimed at protecting our natural resources，including numerous species of plants.    5    

7 . When I was a young man, I had a big ego (自负) and very little empathy (同理心). I thought I knew everything. I looked forward to fame and success. I can even remember proudly telling one of my friends in college: “If only everyone listened to me, they would all be happy.” I finally left school, ready to take on the world. Little did I know the world was about to take on me.

In the years following college, instead of success, I found struggles. I had trouble finding work. The jobs I did work at were either temporary or back-breaking and none of them paid well. When my wife and I had children, we were shocked to learn that not one but both of our sons had autis (自闭症) and would need to be taken care of for the rest of their lives. I had no idea why this had happened to us and I was very angry with the world.

In time, however, I began to change. My formerly massive ego was shrinking fast and my empathy was beginning to grow. Instead of finding joy in success, I found it in moments of love. Playing and laughing with my sons brought me so much happiness. My boys taught me more about peace, patience, kindness, joy, and unconditional love than I could have ever learned on my own. I began to share the lessons I learned through my writing and my life.

I finally realized that my purpose in this world had nothing to do with fame or success but everything to do with allowing love and light into my life and sharing it with everyone I could.