问题 填空题

国家游泳中心“水立方”体现了“科技奥运、人文奥运、绿色奥运”理念,建造时大量使用了一种轻型膜材料,该材料具有强度特别大、密度 ______(填“小’’或“大”)的特性;“水立方”蓄水量近104m3,水重为 ______N,外侧应用了LED照明技术,晚间可发出红、蓝、______三种色光,按比例搭配可实现各种变色,达到“变幻莫测、流光溢彩”的效果.

答案

因为密度是物质的一种特性,根据密度公式变形m=ρV可知,在体积一定的情况下,密度越小,质量越小,那么水立方对地面的压力越小,所以建造时使用轻型膜材料;

由ρ=

m
V
得,m=ρV=1.0×103kg/m3×104m3=107kg,

G=mg=107kg×10N/kg=108N;

因为红、绿、蓝三种色光无法被分解,故称“三原色光”,三原色光中任意两种色光等量相加,则成为三原色光中另一种色光的互补色光,所以按比例搭配可实现各种变色,达到“变幻莫测、流光溢彩”的效果.

故答案为:小;108;绿.

选择题
单项选择题

As the pace of life continues to increase, we are fast losing the art of relaxation. (1) you are in the habit of rushing through life, being on the go from morning till night, it is hard to (2) down. But relaxation is (3) for a healthy mind and body.Stress is a (4) part of everyday life and there is no way to (5) it. In fact,it is not the bad thing that it is often supposed to be. A (6) amount of stress is important to provide motivation and give (7) to life. It is only when the stress gets out of control (8) it can lead to poor performance and (9) health.The amount of stress a person can bear(10) very much on the individual. Some people are not afraid of stress, and such (11) are obviously chief material for managerial responsibilities. Others lose heart at first (12) of unusual difficulties. When exposed to stress, in (13) form, we react both chemically and physically. In fact we (14) a choice between escape and fight. But in more ancient days they made the (15) between life and death. The crises (危机)we meet today are (16) to be so extreme,but however little the stress,it requires the same response. It is when such a reaction (17) long,through continued exposure to stress,that health becomes (18) .Such serious conditions as high blood pressure and heart diseases have (19) links with stress. (20) we canno! remove stress from our lives we need to find ways to deal with it.It would be unwise to do so even it we could.So what do you think of stressWhat is your way to deal with it.

 

第(16)空应选择()

A.unlikely

B.likely

C.necessary

D.probable