1) This important feature makes power lines able to transport electric energy without any problem connected with dissipation of energy. They are useful in the aerospace industry because they<~~who are "they"? can keep a large amount of electric energy without any dissipation.
2) Therefore, astronauts can take a lot of energy in the space and keep it for a long time without increasing the rocketís weight or losing too much space. Finally, they can build a powerful computer processor, which is able to make a lot of calculations in a short time.
3) The use of drug during in the Vietnam War.
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4) Restriction of immigration in the Us in the twenties.
There are several in there.