3 . If you frequent any kind of public transportation, then you’re well aware of certain types of passengers and passenger habits that are annoying. But it’s not just other passengers that get angry, there are certain things that drive the train attendant crazy.     1    . Maybe next time you’ll be able to spot the people doing some of these on the train.

We’ve all been there in that moment when someone boards a train trying to take several huge items with them to wherever they’re trying to go. They wind up taking up way too much space and blocking seats.    2    . Train attendants are the ones who bear the brunt of it (首当其冲) because they have to figure out how to deal with this person’s stuff without upsetting all the other passengers. It adds unnecessary conflict and makes the attendant’s job much harder.

    3    . It’s a totally different thing to be eating a big meal consisting of last night’s dinner leftovers. Not only is it typically unsettling for other passengers who then have to smell leftover chicken and whatever else you’re eating, but it’s bound to make a mess that attendants will then have to clean up after they depart the train.

For some reason, people have a bad habit of talking very loudly to one another to a point where you can hear them from opposite sides of the train cart (车厢). This goes for playing music as well. Some people like to play music through their phone. This really bothers fellow passengers on the train.     5    ? The train attendant.

4 . Volunteers are the lifeblood of nonprofit (非营利的) organizations, but COVID-19 makes it difficult for them to take part, especially for older people. As a result, nonprofit organizations are meeting the challenge of finding new, safe ways to engage with older volunteers.

“COVID-19 has been a real blow to most communities, seriously blocking volunteer participation, but our society needs the talent of these people,” said Marc Freedman, the founder of Encore.org, a nonprofit trying to bridge generational divides. “We know from decades of research that strong social connections and a reason to get up in the morning are key to our well-being as we age,” he added. “So we need to give up the idea of ‘stay safe and stay out of the way.’”

Like so much of life in COVID-19, volunteer work has largely moved online. But technology can be a barrier for many older adults — both those who offer and those who receive volunteer services. They are less likely to get and take advantage of the latest technology. Last year 59 percent of Americans age 65 and older had broadband (宽带) Internet connections, about 20 percentage points fewer than those in younger age groups.

None of that has stopped elderly volunteers like Paula Brynen, a 65-year-old Los Angeles resident. Before COVID-19, she volunteered for the Leukemia & Lymphoma Society’s (LLS’s) Light The Night, an annual fund-raising walk at which participants carry glowing lanterns. Ms. Brynen would help out with setting up the event; nowadays, she focuses on another task. “They usually give volunteers a small list of calls to make,” she said, “but because I worked in fund-raising and have no problem ringing up, they gave me 50 names this year.”

Meanwhile, she is working as a mentor (导师) with Table Wisdom, a St. Louis-based nonprofit that matches older adults with students and young professionals. She connects each week via Zoom with a young environmental engineer in Colombia. “We talk about politics and movie recommendations — I’ve learned a lot about Colombia, and she’s learned about things like Los Angeles’s culture.”

8 . When is a kid not a kid anymore? If you asked my 12-year-old daughter, the magical age would be 13, when you can no longer be considered a “child”. If you asked my 15-year-old niece, the age would be 16, when she will be able to drive a car and get an after-school job. According to the U. S. government, a child officially becomes an adult when they turn 18. That’s when they can vote. But even though an 18-year-old starts paying taxes, the government does not consider that person mature enough to buy a beer. Still, even a kid who can buy a beer is not old enough to rent a car.

Scientists have learned from a new study that when kids are around 18, their prefrontal cortex, which helps control impulses, solve problems, and organize behavior, is only halfway developed. That’s not to say that kids in their late teens and early 20s can’t take on these tasks, but it means that it’s harder for them to do so - at least until around age 25 or so when this area of the brain fully develops.

“What we’re really saying is that to have a definition of when you move from childhood to adulthood looks absurd,” Peter Jones from the University of Cambridge said. “It’s a much more nuanced (微妙的) change that takes place over thirty years.”

This isn’t a news flash for parents who have watched their teens take crazy risks while seeming unable to get their lives together until they’re older. But this information throws new light on the way kids without as much support are treated. In the foster (寄养的) care system, once a child turns 18, he can no longer receive state-backed support. And many people think this is too early for a teen to be on his own, especially a teen who has experienced a painful childhood. Because of this, some foster care advocates think it makes more sense for 25 to be the new legal age of adulthood.