【正确答案】According to the lecturer, there are two major criteria for using an older research reference. First, she mentions, and I'm quoting here, the "potential for change." For example, research on diet may be too old after thirty years because many changes have occurred in dietary practices during that time, but research on language development may be okay because fewer changes have taken place in language acquisition in the same number of years. The other criteria requires that you first identify the research as a conclusion or an opinion. Because, uh, in general, a conclusion may be outdated when a newer study is published, but an opinion credited to a person with the date of the opinion in the citation, um, that's correct over time. In other words, there's no exact number of years to decide whether a reference is acceptable so the date isn't as significant as the criteria. So, an older study can be used if changes in the research haven't taken place or if the results are worded as opinions with the dates cited.

【答案解析】[听力原文] Well, first of all, you have to understand that there's no hard and fast rule for deciding when a research reference is too old. But that doesn't help you much. So, I'll try to give you a couple of guidelines, and then you'll just have to use good judgement. Okay, let's just say for our purposes, that the research is thirty years old. Then the next thing to think about is whether any changes have occurred in society to call the data into question. For example, in a study that looks at diet, we know logically that many changes have occurred in eating patterns over the past thirty years, so this study would probably be outdated. But a study of, say, uh, language development may be okay because the way that babies learn their native language hasn't changed much in the same period of time. So, what I'm saying is...the date is less important than the potential for change. Okay, then the second criteria to consider is whether the citation is a finding or an opinion. If you have a study that indicates, uh, for example, that college students are drinking more, that's a finding, but if you have a statement by the researcher that drinking is the most serious problem on campus, then you have an opinion. And opinions are accurate over the years as long as they're attributed to the person and the date is cited. But the finding for an older study may be too old. In that case, it's probably better to use a more recent study. Using the main points and examples from the lecture, describe the two criteria for using an older research reference presented by the professor.