There has been, over the years a lot of turf battles between the SEC and the CFTC because it's sometimes unclear whether something is a security or a futures.

历年来,证券交易委员会和期货交易委员会的领域战争层出不穷,因为有时候很难说,一个东西究竟是证券还是期货。

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So sometimes, if you miss a class, you can just kind of check in earlier years, like lectures,

所以有时候，如果你错过了一节课，你可以看看前几年的讲座，

开放式的课程？ - SpeakingMax英语口语达人

Sometimes it takes 4 or 5 years in order to get some level of competency.

有时候它需要4到5年才能达到一定的水平，

学第二外语的时候 - SpeakingMax英语口语达人