题目内容：

When you practice reading with passages shorter than book length, do not try to take in each word separately, one after the other. It is much more difficult to grasp the broad theme of the passage this way, and you will also get the stuck on individual words which may not be absolutely essential to a general understanding of the passage. It is a good idea to skim through the passage very quickly first to get the general idea of each paragraph. Titles, paragraph headings and emphasized word can be a great help in getting this skeleton outline of the passage. It is surprising how many people do not read titles, introductions or paragraph headings. Can you, without looking back, remember the title of this passage and the heading of this paragraph?

Most paragraphs of a passage or chapter have a 'topic sentence' which expresses the central idea. The remaining sentence expand or support that idea. It has been estimated that between 60% and 90% of all expositive（说明的）paragraphs in English have the topic sentence first. Always pay special attention to the first sentence of a paragraph; it is most likely to give you the main idea.

Sometimes , though , the first sentence in the paragraph does not have the feel of 'main idea' sentence. It does not seem to give us enough new information to justify a paragraph. The next most likely place to look for the topic sentence is the last sentence of the paragraph.

Remember that the opening and closing paragraphs of a passage or chapter are particularly important . The opening paragraph suggests the general direction and content of the piece, while the closing paragraph often summarizes the very essence （精髓）.

1.It is a good idea to skim through a passage quickly first ________.

A．at about 350 w. P.m.(words per minute)

B．to get the general idea of each paragraph

C．so that you can take in each word separately

D．to make sure you get to the end at least once

2.The topic sentence of an expository paragraph in English_______.

A．usually comes in the middle

B．is most likely to be found at the end

C．is most often at the beginning

D．is usually left out in expository writing

3.Most expository paragraphs in English have a clearly defined topic sentence. In such paragraphs the topic sentence comes first ________.

A．in about 40% of cases                    B．in about 80% of cases

C．in about 20% cases                      D．very rarely

4.Some times we know the first sentence is not the topic sentence because ________.

A．it does not seem to give us enough new information

B．it is not long enough

C．it does not come at the beginning

D．it does not make complete sentence