通常我们认为main idea作为lecture和conversation的第一题，应该是肯定要对的。但是事实上我们往往容易错的是第一题。为什么?有什么理由整篇文章都感觉听懂了，居然做错了第一题?我们来看看做题的几个误区：
误区一
从OG的题型分类上大家可以看到main idea属于basic comprehension的，包括两种：gist content & gist purpose。我们要先弄清楚这两个之间有什么区别?看看OG的解说：
内容主旨题：内容主旨题要求考生理解讲座或对话的主旨大意。材料有时会明确地提出主旨，有时则会很含蓄。内容主旨题会要求考生对所听到的信息进行归纳总结。
n 典型问法：
Ø What problem does the man have?
Ø What are the speakers mainly discussing?
Ø What is the main topic of the lecture?
Ø What is the lecture mainly about?
Ø What aspect of X does the professor mainly discuss?
目的主旨题：目的主旨题主要考查的是对话的目的而非内容。此类问题较有可能出现在对话中，但偶尔也会出现在讲座中。
n 典型问法：
Ø Why does the student visit the professor?
Ø Why does the student visit the registrar’s office?
Ø Why did the professor ask to see the student?
Ø Why does the professor explain X?
OG典型的提问法里我们会看到，不管是conversation还是lecture都有可能考查content，提问法里以what开头;反过来，purpose都是以why来提问的且以conversation为主的，所以同学在做题的时候要记得看清楚第一题到底是问what还是why，what则通常选内容，答案可能是在开头也可能自己归纳，why则选目的通常在开头。
同学们可能会觉得都是main idea都是主旨，应该没什么区别?举个例子来看看，假如我和A同学start a conversation说，A能不能借100块给我?然后开始七聊八聊恒大踢球赢了，各种兴奋……问目的我们要答的是借钱，问内容我们要答的是恒大。That’s the difference.所以我们在做题的时候要区分清楚what和why。
误区二
不是所有的lecture都要问content，TPO经常是换着来问的What is the main purpose of the lecture?
比如：
12. What is the main purpose of the lecture? (TPO10L2)
A To describe the trade in food crops between Europe and Americas
B To describe the introduction of American food crops to Europeans
C To describe the influence of American food crops on traditional Europeans
D To describe the difficulties of growing American food crops in European climates
解析：这是一道同学们很容易做错的题目，大部分都爱选C，选完还特别肯定自己没错，题目要求是purpose，而C项表达的是文章的后半部分的内容，food对欧洲历史的影响，而非题干所要的purpose。整个lecture讲述的是美国食物被引入欧洲的情况，正解就只有B。
误区三
总选择清晰的detail，失分!用排除法。
从上述的OG给出的说法，我们知道main idea有时候会明确给出，有时候比较含蓄，要自己总结归纳。大家心里犯愁了以为听得清楚的，或者反复听到过的内容就一定对了，其实不然。
例1 why does the man go to see his professor? (OG第二版P157track1)
A To borrow some charts and graphs from her
B To ask her to explain some statistical procedures
C To talk about a report he is writing
D To discuss a grade he got on a paper
正解是C，有些同学总是选B，他们分得清楚文章开头没有出现过A/D两项，觉得C概括得太厉害，感觉听到了statistical procedures，其实听到的是：
S: Uh, excuse me,Professor Thompson. I know your office hours are tomorrow,but was wondering if you had a few minutes free now to discuss something.
P: Sure,John. What did you want to talk?
S: Well,I have some quick questions about how to write up the research project I did this semester about climate variations.
把research project听成procedure了。听错了是硬伤，继续精听!巧的同学是听how to write来判断的，而且没有ask to explain的迹象。
例2 What is the purpose of the lecture? (TPO1L1)
A To explain the difference between two artistic styles
B To describe a new art gallery to the class
C To introduce an artist’s work to the class
D To show how artists’ styles can evolve over time
正解C。A是大家最容易选的，套回笔记看看全文有没有对比过异同点，没有，只介绍了两幅画，同样的，B、D都没有。
例3 What is the main purpose of the lecture? (TPO18L3)
A To explore the use of spices in cooking in the Middle Ages
B To explain the significance of spices for medieval society
C To describe how the spice trade evolved in medieval Europe
D To examine changes in the role that spices played in the Middle Age
正解B。A讲cooking是细节点，C讲trade是细节点，D更可以排除spices的role没有change，spices change了欧洲人的生活。
以上总结的是做主旨题的三大误区。我们有时候很难自己归纳出主旨，大家可以使用排除法，明确三项是错误的，选那个我们不太确定的。
排除以后还可以检验我们不确定的那一项是否一定是正确答案。1 该选项是否带有概括性，是否存在带有summary性质的词，这个词能不能概括整篇文章，还是只能概括其中一个清晰的detail;2 选项有summary是不是有具体的限定成分，限定成分表述往往是有误的。
例What is the professor mainly discussing? (OG第二版P166track5)
A The development of motor skills in children
B How psychologists measure muscle activity in the throat
C A theory about the relationship between muscle activity and thinking
D A study on deaf people’s problem-solving techniques
正解C。A、D没有提过，B项限定成分in the throat，C项有概括性质。
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