By 1978, in the USA, the use of CFCs in aerosol propellants was banned.美国自1978年起禁止在喷雾剂压缩气体中使用含氯氟烃。This law closely resembles that obtained with conventional propellants.这种规律非常类似于用普通推进剂所得出的规律.The lighter version used liqu...
The lighter version used liquid hydrogen, the heavier used hypergolic propellants.较轻的推进器采用液态氢, 较重的采用自燃推进剂.Pressure - fed engines are particularly susceptible to dissolved gas in the propellants.挤压 式 发动机对推进剂中溶解的气体特别敏感.Thi...
It's easy to be concerned with problems across the other side of the world and not see the poverty and unhappiness on your own doorstep.人们往往会关注世界另一端的问题,而忽略了家门口的贫困和不幸.Chapter 16 will be concerned with interpretation ...
People are leaving in their thousands while the going is good.成千上万的人趁着局势稳定赶紧撤离。I had the good fortune to be selected...我有幸被选中。The results will decide if he will win a place at a good university...这些成绩将决定他能否上一所好大学。That wo...