3）表示并列关系的词语：one，another，other，first of all，in addition，moreover，besides，
例 1：Nuclear power could be a source of energy for many years to come. However, there are
several problems which have to be solved. The first one is the disposal of radioactive waste. This
is highly harmful and remains active for thousands of years. Another problem is the possibility of
an accident that liberates radioactive material into the environment. Still another problem with
the development of nuclear energy is the danger of its being turned into the production of atomic
文中 “However, there are several problems which have to be solved” 是段落的主题句，表
题，段落中使用的连接词是 the first one, another, still another.
例 2：John likes to fly as an airline passenger at night rather than during the day for four
reasons. First, it costs less. For example, he would have to pay $ 125 to fly from San Francisco to Mexico City by day. But by night, the fare is $75. Second, the plane is less crowded on night flights. Because of this, Paulo rarely has to sit three abreast when he flies at night. As a result, he has more room to stretch out. Third, night flights are quieter than day flights. For instance, John can study or read without being distracted by loud conversations or by people walking up and down the aisle. Fourth ，passengers on night flights can usually sleep quite comfortably if theywant to.They do this by folding up the armrests between three empty seats. This allows a passenger to lie down for a nap under a blanket. For these reasons, John rarely reserves a daytime flight on a commercial airline.
例如：Unlike human beings, animals communicate with one another by means of cries: for
example, many birds utter warning calls at the approach of danger；apes utter different cries, such as expression of anger, fear and pleasure. But these various means of communication differ in important ways from human language. For instance, animals' cries are not articulate. This means, basically, that they lack structure. They lack, for example, the kind of structure given by the contrast between vowel and consonants They also lack the kind of structure that enables us to divide a human utterance into words．
John likes to fly as an airline passenger at night rather than during the day for four reasons.
First, it costs less. For example, he would have to pay $125 to fly from San Francisco to Mexico City by day. But by night, the fare is $75. Second, the plane is less crowded on night flights...
some, about, or so, approximately, the approximate number of, the average of, the proportion
of… to... in the proportion / ratio of...
以下例文的作者用 estimated that 和 said 分别间接、 直接地引述电脑专家 Donn B. Parker 的言论来说明段落主题。
The costs to the victims of computer crime are very high. In his book, computer expert Done
B. Parker estimated that financial losses to business from computer thefts would exceed $ 10
billion in 1978. Although Parker's estimate is based on documented cases, no one really knows the
extent of computer crime because thefts by computers are almost impossible to discover. “There is just no reliable way to detect computer thefts Parker said.” It is not just the money they control, they control data, and data is power.”
said that, as ... said, continue to say that, stated (that) ,as stated, believe (that)
见，也是说理性最强的一种。下例以人们很难客观地评价某一个人为主题，采用了 Jack 和Sam 两个人的实例说明这一观点。
It is very difficult to evaluate another person's performance objectively. For example,Jack recently wrote irresponsible remarks about her instructor because she was failing the course. Her friend Sam wrote a marvelous description of the same instructor because he was receiving an A in the course. Both Jack and Sam were not fairly evaluating the instructor. They were influenced by the grades they were earning and were biased in their judgment.
① for example, for instance, for another example, that is, namely, such as, like
② This can be shown / illustrated by...
③ To take ... as an example,
④ One example is…; another example is ...
⑤ A is just an illustration of B.
⑥ A good example of X is ...
⑦ There is enough evidence to show / support / indicate that…