Passage 2 Questions 6 to 10 are based on the following passage:
When we’re learning a foreign language, making sense of what we hear is the first step toward fluency. It sounds obvious, but until recently, we didn’t know much about how listening works. New research demonstrates that effective listening involves more than simply hearing the words that float past our ears. Rather, it’s an active process of receiving information and making meaning. This kind of engaged listening is a skill that’s as critical for learning a range of subjects at school and work as it is for learning to understand a foreign tongue.
(78) Studies of skilled language learners have identified specific listening strategies that lead to superior comprehension. Last year, for example, University of Ottawa researcher Larry Vandergrift published his study of 106 undergraduates who were learning French as a second language. Half of the students were taught in a conventional fashion, listening to and practicing texts spoken aloud. The other half, possessing the same initial (最初的) skill level and taught by the same teacher, were given detailed instruction on how to listen. It mined out that the second group “significantly outperformed”(胜过) the first one on a test of comprehension.
So what are these listening strategies Skilled learners go into a listening class with a sense of what they want to get out of it. (79) They set a goal for their listening and they generate predictions about what the speaker will say. Before the talking begins, they mentally review what they already know about the subject, and form an intention to “listen out for” what’s important or relevant. Once they begin listening, these learners maintain their focus; if their attention wanders, they bring it back to the words being spoken. They don’t allow themselves to be thrown off by confusing or unfamiliar details. Instead, they take note of what they don’t understand and make inferences about what those things might mean, based on other clues available to them: their previous knowledge of the subject, the context (语境) of the talk,, the identity of the speaker, and so on.

What is the main idea of this passage（）