Passage2
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.
According?to?the?passage,a?life?be?first?of?all（ ）.
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。
将自然数1~100分别写在完全相同的100张卡片上，然后打乱卡片，先后随机取出4张，问这4张先后取出的卡片上的数字呈增序的几率是多少？（）
市场经济体制下，财政具有的职能有( )。
箱子里面有红、白两种玻璃球，红球数比白球数的3倍多两个，每次从箱子里取出7个白球、15个红球。如果经过若干次以后，箱子里只剩下3个白球、53个红球，那么，箱子里原有红球比白球多多少个?
如果一国货币汇率上升，即对外升值，就可能会导致（ ）。
根据《中华人民共和国中国人民银行法》的规定，我国货币政策的最终目标是（ ），并以此促进经济增长。
下列关于公司的表述，正确的是（）
以下各项列举了我国常见气象灾害与其发生地区的对应关系，其中正确的一项是（）
根据电视收视率调査，看体育节目的观众中青年人比中老年人要多。
由此可推断出（）
—种海洋蜗牛产生的毒素含有多种蛋白，把其中的一种给老鼠注射后，会使有两星期大或更小的老鼠陷入睡眠状态，而使大一点的老鼠躲藏起来。当老鼠受到突然的严重威胁时，非常小的那些老鼠的反应是呆住，而较大的那些老鼠会逃跑。
以上陈述的事实最有力地支持了以下哪项假说？（）
