对熟悉的事情的应付自如，并能用英文解释。

I can talk about tact or theories I know well and explain them in English.

理论在本质上是对熟悉了的现实的一种抽象和符号化的表达。

Essentially a theory is an abstract symbolic representation of what is conceived to be reality.

这么看来，5至20美元的信用额正是对熟悉新的商业渠道或搜索引擎所耗时间的合理补偿。

Seen in this light, a credit of $ 5 to $ 20 may be fair compensation for the time lost in switching to a new merchant portal or search engine.