There are lots of ways of greeting in English which can be used in both formal and informal situations, eg: How are you doing?

在英语中有很多问候的方式可以用在正式和非正式的场合里。

Support informal communities of practice. Create others where you there are gaps.

支持非正式社团的实践活动。在有差距处，创建其他社团。

Though you can learn informally from most any website, there are also a few websites that focus on helping you learn about informal learning.

尽管你能在多数任意网站开展非正式学习，还是有一些网站专注于帮助你了解非正式学习。