When you are a kid, gaining a best friend forever can happen in a single play date. But when you grow up to be an adult, making and maintaining friendships gets harder. So how much quality time (优质时光) do you need before that stranger becomes your friend? A new study recently found that, on average, it takes about 50 hours with someone before you consider them a casual (感情不深的) friend, about 90 hours before you become real friends, and about 200 hours to become close friends.

The study’s author Jeffrey Hall, a communications professor, invited adults who are eager to make friends to take part in two experiments — people who had just moved to a new city in the past six months and college freshmen. He asked them to rate and track the degree of closeness and time spent together with a new person. “Results suggest that the chance of changing from casual friend to real friend is greater than 50% after around 80-100 hours together,” said Hall.

The study found that the amount of time spent talking together, or the fact that you spent time at school or work with them, was unrelated to friendship closeness. “It is really easy to spend a lot of time with people as they are routinely in the same place at the same time as you,” Hall said. “However, my study shows you can have workmates you spend hundreds and hundreds of hours with and still not develop a friendship.”

You do not need to become best friends with your workmates to develop meaningful relationships with them. But for those of us hoping to change from “girl who I eat lunch at work with” to “friend I can depend on,” Hall suggests that you need to take the relationship out of the workplace for it to become a friendship. The participants who did activities outside of work with someone, such as being invited to have lunch in their home, were more likely to develop deeper relationships with them.

Becky had everything Sarah wanted: a pool in her backyard, popularity, and new clothes. Worse, it seemed (at least to Sarah) that Becky had the Midas touch. Everything she touched turned to gold. She won the class lottery and with it $50! She won every race she entered, every art competition, and every award the school offered. She had all the luck in the world.

Sarah was an only child. She wore hand-me-downs from her older cousin Clementine. She didn't have many friends. Her best friend Kiara was really the best in a lot of ways: kind,generous, and loyal. Just the kind of person you would want for a best friend. But Sarah most certainly did not have good luck. She never won anything. On the days she carried an umbrella, it never rained; on the days she forgot her umbrella, dark ruin clouds seemed to follow her around.

One rainy day in April, though, Sarah and Becky swapped luck. That's how Sarah thought of it anyway. It wasn't expected, and it certainly wasn't planned. But after weeks of wishing for it, Sarah woke up and things felt different. She felt lucky.

She rolled out of bed and noticed a small package on her desk. She opened it: it was a brand new dress, the same one she had been eyeing for weeks. Mom!" she called. Did you get me this dress?”

“It's from your grandmother.” her mother called back," Early birthday gift!”

Sarah shrugged. Her birthday wasn’t until August..

And it didn’t stop there. On the school bus, Carlos, the most popular boy in school, saved her a seat. Then Mrs. Nelson picked her—yes, her!-- to take care of the class rabbit over the weekend. But the best part of the day was art class. Mr. Rodriguez, her art teacher, walked around the room slowly. Sarah hadn't spent much time on her project. But it was still pretty, still unique. Mr. Rodriguez walked past Becky's art project and didn't even pause. Becky looked devastated. Her hair was still wet from that morning's rain. She had forgotten to bring an umbrella.

“Well, class!” Mr. Rodriguez said." I think our winner for this month is Sarah! Excellent work, Sarah--this shows a lot of progress!"

Sarah smiled proudly, “Guess you have some competition," she whispered to Becky.

Sarah was on top of the world. Today, she felt like a better-than-average fourth grader, possibly the best fourth grader who had ever existed. She wondered what was next.

Becky, she noticed had spent most of the day sulking(生闷气的)."Let someone else have a shot at being lucky for once," Sarah thought to herself. Then she noticed that Becky was crying. Small tears dropped down onto her t-shirts.

“What’s wrong?” Sarah asked.

“I just spent a lot of time on that project," Becky said between hiccupped sobs.

Sarah was beginning to feel awful: After all she hadn’t spent much time on her project at all.

Then she felt Kiara tap on her shoulder. “You know, Sarah,” Kiara started. She looked angry and hurt at the same time. “You haven’t been very nice today. You’ve been acting like…like you’re the best person in the world,” She shook her head. “This isn’t just like you at all.”

Now Sarah felt even worse. It was one thing to have the class pet dislike you, but another thing entirely to disappoint you best friend, “I’m sorry, Kiara,” she said. “It’s just been a weird day.”

She walked over to Becky and gave her a hug. “Don’t worry,” she whispered, “your luck will change soon enough.” Luck, Sarah was beginning to think, was overrated.