3 . Is there a link between social media and depression? Do Facebook and Instagram have a negative impact on your mental health? It’s complicated.

Sometimes, looking through Instagram just makes you feel bad. You try not to envy your friends, but they always seem to be traveling somewhere cool, eating something fancy, or looking cute in perfect just-rolled-out-of-bed hair. On the other hand, there are times when you laugh at funny memes (表情包), catch up with old friends, and feel happy to belong to fun social media communities. Clearly, social media isn’t all bad.

People are increasingly suspecting that there’re potential problems of social media. Things like cyberbullying (网上欺凌) , screen addiction, and being exposed to endless filtered images (美颜) that make it impossible not to make comparisons between yourself and others often make the news. In July, a big study came out in the journal JAMA titled “Association of Screen Time and Depression in Adolescence.” This big headline seems to confirm what a lot of people have been saying — screen time is horrible for young people.

The study followed over 3,800 adolescents over four years as part of a drug and alcohol prevention program. Part of what the investigators measured was the teens’ amount of screen time, including time spent on social media, as well as their levels of depression symptoms. One of their main findings was that higher amounts of social media use were associated with higher levels of depression. That was true both when the researches compared between people and compared each person against their own mental health over time.

Case closed? Not so fast. Before we end the debate once and for all, let’s take a closer look at this and other studies. Let’s ask ourselves: what exactly is the relationship between social media use and depression? It turns out there are several warnings.

5 . It was a cold March day in High Point, North Carolina. The girls on the Wesleyan Academy softball team were waiting for their next turns at bat during practice, stamping their feet to stay warm. Eighth-grader Taylor Bisbee shivered (发抖) a little as she watched her teammate Paris White play. The two didn’t know each other well — Taylor had just moved to town a month or so before.

Suddenly, Paris fell to the ground. “Pairs’s eyes rolled back,” Taylor says. “She started shaking. I knew it was an emergency.”

It certainly was. Paris had suffered a sudden heart failure. Without immediate medical care, Paris would die. At first, no one moved. The girls were in shock. Then the softball coach shouted out, “Does anyone know CPR?”

CPR is a life-saving technique. To do CPR, you press on the sick person’s chest so that blood moves through the body and takes oxygen to organs. Without oxygen，the brain is damaged quickly.

Amazingly, Taylor had just taken a CPR course the day before. Still, she hesitated. She didn’t think she knew it well enough. But when no one else came forward, Taylor ran to Paris and began doing CPR. “It was scary. I knew it was the difference between life and death,” says Taylor.

Taylor’s swift action helped her teammates calm down. One girl called 911. Two more ran to get the school nurse, who brought a defibrillator, an electronic device (器械) that can shock the heart back into work. Luck stayed with them: Paris’s heartbeat returned.

“I know I was really lucky,” Paris says now. “Most people don’t survive this. My team saved my life.”

Experts say Paris is right: For a sudden heart failure, the single best chance for survival is having someone nearby step in and do CPR quickly.

Today, Paris is back on the softball team. Taylor will apply to college soon. She wants to be a nurse. “I feel more confident in my actions now,” Taylor says. “I know I can act under pressure in a scary situation.”

A reporter from Jiangsu Province went to Australia and some other countries with his father for a 3-month trip,     1     turned out to be a miracle (奇迹).

The reporter’s father spent most of his life    2     (work) on the farm. The son started these    3     (amaze) trips with his father because the father got cancer-----a serious    4     (ill). The reporter wanted    5     (take) his father to travel in the hope that his father can find his younger self in his last days. They    6     (travel) more than 13,000 kilometers and took over 110,000    7     (picture) on their trips to different countries. Well, a miracle happened during the “rebirth” trips.     8     their surprise, his father got    9     (good) and became more open-hearted.

He even taught himself to play    10     violin, and then he played it very well after practice. After that miracle trip, now he is expecting another trip to Africa. He is the most stylish dad ever. Time carves (雕刻) the old father’s face but youth flows in his blood. This is the real style.

8 . People have different ways of dealing with a common cold. Some take over-the-counter(非处方的)medicines such as aspirin while others try popular home remedies(治疗)like herbal tea or chicken soup. Yet, here is the tough truth about the common cold: nothing really cures you of it.

So why do people sometimes believe that their remedies work? According to James Taylor, professor at the University of Washington, colds usually go away on their own in about a week, improving a little each day after symptoms peak, so it’s easy to believe it’s medicine rather than time that deserves the credit.

It still seems hard to believe that we can deal with more serious diseases yet we are powerless against something so common as a cold. Recently, scientists came closer to figuring out why. To understand it, you first need to know how antiviral(抗病毒的)drugs work. They attack the virus by attaching to and changing the surface structures of the virus. To do that, the drug must fit and lock into the virus like the right piece of a jigsaw(拼图), which means scientists have to identify the virus and build a 3D model to study its surface before they can design an antiviral drug that is effective enough.

The two cold viruses that scientists had long known about were rhinovirus(鼻病毒)A and B. But they didn’t find out about the existence of a third virus, rhinovirus C until 2006.All three of them contribute to the common cold, but drugs that work well against rhinovirus A and B have little effect when used against rhinovirus C.

“This explains most of the previous failures of drug trials against rhinoviruses,” study leader Professor Ann C. Palmenberg at the University of Wiscons in Madison, US, told Scienc Daily.

Now, more than 10 years after the discovery of rhinovirus C, scientists have finally built a highly detailed 3D model of the virus, showing that the surface of the virus is, as expected,different from that of other cold viruses.

With the model in hand, hopefully a real cure for a common cold is on its way. Soon, we may no longer have to waste our money on medicines that don’t really work.

In December 2019, there was a cluster of pneumonia     1     (case) in China. Investigations found that it was caused by a     2     (previous) unknown virus–now named the 2019 Novel Coronavirus. It     3     (identify) first in China,     4     occurred in a group of people with pneumonia who’d been associated     5    a seafood and live animal market in the city of Wuhan. The disease spread from those who were sick to others,     6     (include) family members and health care staff.     7     (fight) against the epidemic, the Chinese people united even stronger than ever before, and they made     8    . China also helped other countries in the same situation,     9     (make) its positive image all over the world     10    (strengthen).

Face masks are reportedly selling out in     1     (city) across Asia because of the spread of a deadly new coronavirus. But will these masks stop people     2     (catch) the virus thoroughly? We know it is a kind of airborne (空气传播的) virus,     3     can spread easily among people. So it makes sense     4     (cover) your nose and mouth.

Now two main types of face masks are being used to do that. One is the standard surgical mask. But these masks can’t offer full protection     5     airborne viruses. They don’t fully seal off the nose and mouth, so very small particles can simply pass through the material of the masks. These masks also leave the wearers’ eyes     6     (expose), through which the virus can infect them.     7     other type, the N95 mask, is more effective than the surgical mask. They can prevent 95 percent of small particles entering the nose and mouth area. But they won’t work     8     they fit properly. And they aren’t suitable for children or people with     9     (face) hair.

There     10     (be) other precautions (预防措施) people can take to avoid catching the virus, such as avoiding large public gatherings, staying at home and washing hands frequently.