Merchant and passenger ships are generally required to have a life preserver for every person aboard and in many cases, a certain percentage of smaller sizes for children. According to United States requirements, life preservers must design, reversible capable of being quickly adjusted to fit the uninitiated individual, and must be so designed as to support the wearer in the water in an upright or slightly backward position.

Sufficient buoyancy(浮力) to support the wearer should be retained by the life preserver after 48 hours in the water, and it should be reliable even after long period of storage. Thus it should be made of materials resistant to sunlight, gasoline, and oils, and it should be not easily set on fire.?The position in which the life preserver will support a person who jumps or falls into the water is most important, as is its tendency to turn the wearer in the water from a face-down position to an upright or slightly backward position, with his face clear of the water, even when the wearer is exhausted or unconscious.

The method of adjustment to the body should be simple, and self-evident to uninitiated persons even in the dark under the confused conditions, which follow a disaster. Thus, the life be reversible that it is nearly impossible to get it on wrong. Catches, straps, and ties should be kept to a minimum. In addition, the life preserver must be adjustable to the wide variety of shapes and sizes of wearers, since this greatly affects the position of floating and the self-righting qualities. A suitable life also be comfortable to wear at all times, in and out of the water, not so heavy as to encourage to take it off on shipboard while the ship is in danger, nor so burdensome that it hinders a person in the water while trying to swim.

1. The passage is mainly about____.

A) the uses of life preservers

B) the design of life preservers

C) the materials for life preservers

D) the buoyancy of life preservers

2. According to the passage, a life be first of all ____.

A) adjustable B) comfortable C) self-evident D) self-righting

3. United States Coast Guard does NOT require the life preserver to be made ____.

A) with as few strings as possible

B) capable of being worn on both sides

C) according to each wearer's size

D) comfortable and light to wear

4. By “the uninitiated individual” (Para. 1, Line. 4) the author refers to the person ____.

A) who has not been instructed how to use a life preserver

B) who has a little experience in using a life preserver

C) who uses a life preserver without permission

D) who becomes nervous before a disaster

5. What would happen if a person were supported by the life preserver in a wrong position?

A) The waves would move him backwards.

B) The water would choke him.英语四级成绩查询网

C) He would immediately sink to the bottom.

D) He would be exhausted or unconscious.

答案解析:

1. B。文章主要讲述了救生衣的设计。间接题型段首主旨题。C项和D项都是对救生衣设计中设计材料的说明。A项为陷阱，指救生衣的用途，尽管开头提到，但范围不着边际。故只有B是正确选项。

2. D。根据文章，救生衣首先会自动扶正。事实细节题。本文第三段主要讨论救生衣落水位置，应设计的能“自动扶正”,或稍向后仰。B项是对材料的描述，范围太窄，而A和C不合题意，因此D是正确答案。

3. C。美国海岸巡逻队不需要救生衣根据穿戴者的尺寸生产。事实细节题。A项和B项都涉及method，其相关部分见最后一段第三句，A，B，D三项都是文章中提及的，C项与本题无关的内容，因此应该选C。

4. A。“the uninitiated individual”作者指的是不知道怎么使用救生衣的人。语义指代题。根据文章最后一段第一句，我们可推出“the uninitiated individual”就是指的那些不知道怎么使用救生衣的人。故A是正确选项。

5. D。如果一个人没有正确使用救生衣，就会发生什么?细节辨别题。第三段第一句后半句中a face-down position和本题中的 in a wrong position相对应。因此选项D“他可能太累了或者是已经失去知觉”是正确答案。