life expectancy at birth是什么意思

英语翻译
To increase the life expectancy of future bridges,the deterioration process of existing bridges must be well understood and quantified.In other words,new limit states of bridge designs need to be identified,such as the effects of steel member corrosion on bridge performance and foundation scouring effects on the integrity of bridges.It is equally important to establish the relation between the de-icing service for safer and smoother mobility of people and the level of corrosion.
这是一整段
It is equally important to establish the relation between the de-icing service for safer and smoother mobility of people and the level of corrosion.翻译这句话就行了

翻译成汉语，有急用
Life expectancy has been raised considerably. For example,a person born in the United States 80 years ago could expect to live only 47 yeas.Now,however,life expectancy in that country is 74 years.

Life expectancy is now 73 years which is more higher than before due to the medical prograss.
和 Life expectancy is now 73 years ,which is more higher than before due to the medical prograss.的不同,

The place with the highest life expectancy is Beijing 这句话有错误吗?如果有怎么改?

英语翻译
That is your effort-performance expectancy about this particular assignment might be quite low .On the other hand ,if you feel that you are well qualified for the project and that the available resources are adequate,you might assess the probability of your efforts leading to high performance as quite high .In your special-project situation,perhaps your manager has a history of giving rewards,such as recognition and bonuses,to individuals who take on special project.If so,you might assess the performance-outcome expectancy for taking on the project as very high .On the other hand,your past expectancy with special projects may suggest that the manager sometimes arranges for rewards but other times forgets .If that is the case,you might view the performance-outcome expectancy as medium in strength （perhaps a 50-50 probability of being rewarded）.In the worst case ,if your manager never rewards extra effort,you might assess the performance-outcome expectancy as virtually zero .In the special-project example,you might view the prospect of a special bonus from the manager in an extremely positive lithe.On the other hand ,if you were very rich,the bonus may be much less important .You will be fairly highly motivated to pursue the project：“high effort-performance expectancy × high performance-outcome expectancy × high valence = high motivation ”.On the other hand,an assessment of zero for any of the elements will cause the whole equation to equal zero,regardless of the level of the other two elements.

'There is no reason that life expectancy can't continue to go up two to three years per decade,'' 是什么从句
there is no evidence that the speed is slowing 是什么从句

英语翻译
the average life expectancy of a new-born baby at only fourteen years