Here are the last sentences on the same theme.

1) This important feature makes power lines able to transport electric energy without any problem connected with dissipation of energy. They are useful in aerospace industry because they can keep a big amount of electric energy without any dissipation.
2) Therefore the astronauts can take a lot of energy in the space and keep it for a long time without increasing the rocket’s 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.

I also need to find easy, online documentation on the follwng themes:

3) The use of drug during in the Vietnam War.
4) Restriction of immigration in the Us in the twenties.

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 rocket’s 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.

4) Restriction of immigration in the Us in the twenties.
http://www.google.com/search?hl=en&site=&source=hp&q=immigration+to+usa+in+1920s+restrictions&oq=immigration+to+usa+in+1920s+restrictions&aq=f&aqi=&aql=&gs_l=hp.3...1797.16529.0.16775.42.33.1.8.8.0.237.3947.6j26j1.33.0...0.0.ccyUkNb1vyY
There are several in there.

To find easy, online documentation on the themes you mentioned, you can follow these steps:

3) The use of drugs during the Vietnam War:
- Start by searching for reliable sources related to the Vietnam War and drug use. The keywords you can use in your search include "Vietnam War drug use," "drug abuse in Vietnam War," or "drugs and soldiers in Vietnam War."
- Look for reputable websites that provide historical context and information, such as official government publications, educational institutions, or well-known organizations specializing in historical research.
- Verify the credibility of the sources you find by checking if they are authored by experts, referenced, and published by reputable entities.
- Read the articles, reports, or books you find to gather information on the topic. Take notes and extract the relevant information for your needs.
- Compile the information you gather, and if needed, use it to create your own document or summarize it for your purposes.

4) Restriction of immigration in the US in the twenties:
- Begin your search by using keywords such as "US immigration restriction 1920s," "immigration acts in the 1920s," or "immigration policies in the 1920s."
- Look for websites that provide historical information from reliable sources like government archives, academic institutions, or reputable historians.
- Check if the sources are credible, authoritative, and well-referenced.
- Read through the articles, government reports, or books you find to gain a deeper understanding of the topic. Take note of the key points and relevant information.
- Organize the information you gather and use it to create your own document or summarize it for your needs.

Remember to critically evaluate the sources you find and cross-reference information from multiple sources to ensure accuracy and reliability.