A University of Kansas professor has defined the amount of time necessary to make a friend and how long it typically takes to move through different stages of friendship.
近日，美国堪萨斯大学的一位教授定义了交友所需的必要时间，以及发展至友谊不同阶段通常所需的时间长度。

In a new paper published in the Journal of Social and Personal Relationships, Professor Jeffrey Hall found that it takes roughly 50 hours of time together to move from mere acquaintance to casual friend, 90 hours to go from that stage to simple "friend" status, and more than 200 hours to become "good friends".
在《社会与人际关系杂志》最新发表的论文中，杰弗理·霍尔教授发现，两位点头之交成为一般朋友需要相处约50个小时，变成真正意义上的朋友需要90小时，成为好友则需要超过200小时。

This means time spent hanging out, joking around, playing video games and the like. Hours spent working together just don't count as much.
这里指的时间是花在诸如一起外出、开玩笑、玩视频游戏等活动上的时间，一起工作的时间不算。

Coworkers can be still become friends, of course, but you need to spend time together outside of the workplace for it to happen.
当然，同事之间仍然可以成为朋友，但你需要在工作场所以外多找机会相处才行。

"The amount of time and the type of activity shared with a partner can be thought of as strategic investments towards long-term belongingness needs," wrote Hall.
霍尔写道：“与伙伴一起度过的时间和与之共同进行的活动类型，都可视作对长期归属感需要的战略投资。”

Give the people you like your time, hope they'll give you theirs, and stay focused on having a good time. Friendship will follow.
给你喜欢的人你的时间，希望他们会给你他们的时间，保持专注并玩得开心。友谊也必将随之而来。