Possible description of a rocket: A large, cylindrical, flying vehicle that is used to transport astronauts, satellites and other cargo into space.

Great description, Екатерина! Brief and concise. It transmits the idea very simply and easily. Remember the articles: A rocket is a flying device...

Ok Denis. Remember the articles: singular, nonspecific - "a". A rocket. If you talk about rockets, plural, in general, then no article - Rockets are... A rocket is a really large machine. It is used for flying to space. It is a very expensive machine, (adjectives always before the noun), and every country cannot launch a rocket. ("Cannot" is normally one word unless you want to give emphasis to the negative, "not".) A rocket carries astronauts or satellites into space. An engine is at the bottom part of the rocket and when the rocket reaches space the engine is pushed from (you could say "detached from") the rocket.

Rocket is flying device to travel into space.

Rocket is really large machine. It is used for flying at the space. It machine is very expensive and every country can not launch a rocket. Rocket carries astronauts or satellites to the space. An engine is bottom part of rocket and when rocket reaches to space then engine is pushed from rocket.