I guess Krashen's model has provided a useful framework for second language learning.

我想克拉申的模型为第二语言学习提供了一个有用的框架。

Earlier, we saw that according to Krashen, acquisition, but not learning can trigger improvement in a language.

在此之前，根据克拉申的说法，我们知道，能够提高一门语言的是习得，而不是学习。

Yes, many theories and models have been put forward by researchers so far. Today, I'd like to mention the five hypotheses proposed by Stephen Krashen.

嗯，目前研究者们已经提出了很多理论和模型。今天，我想讲讲斯蒂芬·克拉申提出的五个假设。

In Krashen's book, Principles and Practice in Second Language acquisition, he says “Acquisition of language is a natural, intuitive, and subconscious process of which individuals need not be aware.”

在克拉申的《第二语言习得的原则与实践》一书中，他说“语言习得是一个自然的、直觉的、潜意识的过程，个人不需要意识到这一过程。”