第三大题 标出主题句(本大题共3小题，每小题5分，共15分)
一， 考核知识点：考查对主题句(topic sentence)特征的掌握以及识别主题句的能力。
●试题：
16. Choose the best topic sentence from the group below. Write the letter of the choice in the blank.
[A] Temperatures in the western hemisphere have stayed the same in the past century.
Temperatures in the western hemisphere are being studied by scientists.
[C] Temperatures in the western hemisphere are gradually warming.
[D] Temperatures in the western hemisphere are being changed.
●答案：
16. [C] Temperatures in the western hemisphere are gradually warming.
●解题关键：
(1) 了解主题句(topic sentence)的特征：主题句(topic sentence)是一个段落中最重要的句子，它的作用是概括一个段落的中心意思，所以往往是表示一般概念的句子。范围太大或太小，都会使作者无法展开段落，必须通过某些限制性词语将内容范围限制到一定程度，因此主题句应包括主题和限制性词语。从语义层次分析，主题句是一个概括性的语句(general statement)，它必须包涵段落要谈论的主体(subject)和这个主体的某一所谈论的方面(controlling idea)，即Topic sentence=Subject+Contrlling idea.
(2) 比较16题中的四句，看哪一句既有一定的概括性，又能留出一定的展开余地。
(3) [C]句符合上述的条件，其中Temperatures in the western hemisphere是subject; are gradually warming是controlling idea，有待推展和细节支持。
(4) 其余三句虽也符合主题句“Topic sentence=Subject+Contrlling idea”的特征，但[A]句中have stayed the same in the past century是静态的描述，不利于推展;句中are being studied by scientists意义笼统，缺乏探讨的价值;[D]句中被动语态are being changed的使用使句义不够明晰，令人费解。
二， 考核知识点：考查在段落中寻找主题句(topic sentence)的能力。
●试题：
17. Read the following paragraph and underline the topic sentence.
I don‘t like algebra this semester， and I’m not too found of history. But I‘m enjoying my racquetball class a lot. I’m getting a lot of exercise， and I‘m also enjoying the game. We usually play partners and compete in small tournaments within the class. The competition is fun， and playing partners keeps it relaxed. I also have found that I have some ability in racquetball that I haven’t had in other sports. I may sign up for intermediate racquetball next semester.
●答案：
17. Topic sentence： I‘m enjoying my racquetball class a lot.
●解题关键：
(1) 段落中的主题句(topic sentence)是全段的统领，它说明段落的中心思想和作者写作的目的。段落的其余句子必须与主题句密切相关，共同阐明、证实主题句。因此，主题句具有概括性，支配段落中其他各句的走句。
(2) 多数情况下主题句出现在段首，但也可以在段中或段尾。17题段落中的第二句I‘m enjoying my racquetball class a lot包含subject(racquetball class)和controlling idea(I’m enjoying it a lot)，下文各句就enjoying一词展开，详细说明喜欢racquetball class的事实和原因。所以敲定该句为主题句。
●考生典型答题错误分析：
(错误)Topic sentence： I may sign up for intermediate racquetball next semester.
(分析)该句适合做结论句(concluding sentence)，因为它必须依赖前文对enjoying my racquetball class的探讨才有效度。
三， 考核知识点：考查根据段落中的支持句(supporting sentences)来推断主题句(topic sentence)的能力。
●试题：
18. Read the following paragraph carefully and select the best topic sentence from the four possible answers that follow the paragraph.
Topic sentence：
First， there are always customers to be served. I work in a downtown McDonald‘s that gets lots of traffic， and as soon as I serve one customer， there is always another one ready to order. There is constant pressure because I can never step back for a few minutes and relax. Second， I have to put together all of the orders myself. To do that， I have to move all over the serving area： French fries on one side， drinks on the other， and burgers in middle. It’s easy to get sloppy and spill a Coke or throw French fries on the floor. Also， I must always move at a fast pace. McDonald‘s has an image to uphold， and its workers must scurry about like ants. If I don’t move fast enough， some customers will say， “Hey， speed it up，” or “I though McDonald‘s had fast service.” And with all of this nonstop work， I only get one ten-minute break every two hours. However， ten minutes isn’t enough time to rest and feel like getting back to work. It only gives me enough time to realize hoe tired I am， so I go back to work depressed. Finally， my manager really keeps the pressure on. He watches us like a hawk， and every time I do something wrong， he seems to catch it. He also has a reputation for firing people， and he never lets any of the workers feel that their jobs are safe. By the end of the day， I‘m emotionally and physically drained， like everyone else， and we all head out the door grumbling.
[A] The hamburger sold at McDonald‘s is my favorite food.
There are several reasons that I like McDonald‘s.
[C] Working at McDonald‘s is very tiring.
[D] I have no idea about working at McDonald‘s.
●答案：
18. Topic sentence： [C] Working at McDonald‘s is very tiring.
●解题关键：
(1) 明确主题句(topic sentence)与支持句(supporting sentence)的关系：主题句(topic sentence)是统领，起着开宗明义、提纲挈领的作用，其余的与主题相关的支持句(supporting sentences)都围绕主题句来展开，用来阐明、证实主题句。
(2) 18题段落中的各句描述了麦当劳员工工作的情况：店员要不停地接待一个又一个顾客，异常忙碌，身体极度疲劳，还要承受顾客的诸多抱怨和经理的严厉监督。所有这些supporting sentences都用细节支持说明一个事实：在麦当劳工作十分辛苦。故[C]句Working at McDonald‘s is very tiring就是该段落的topic sentence.
(3) [A]、、[D]三句，与段落各支持句内容或不相关或相矛盾，故为错解。
