I belive the answer to the first one is no I would have to assume a habitual zone is one area on a planet. for example, an air conditioned building vs. the Savvanah dessert. However I am not sure maybe other answers will help more on this one. Sorry.... Earth-like planet would of course need water, plant life, animals, oxygen, fossil fuels etc. A challenge we would face on a travel to another liveable planet: do we have engough transportation? engough fuel to make it? How long can we live on this planet? Who or what else is present here? etc. Yes I do think they should discover a planet with earth like qualities befor investing in tools to get us to them. So money is not wasted. (make sure to put this into your own words )
The focusing of conscious awareness on a particular stimulus, as in the cocktail party effect (ability to attend selectively to only one voice among many). thats the answer
The economic crisis in most of the European countries was one of the primary reasons for migration in European countries.
Explanation:
Earlier after the end of second world war, many people migrated from country side to developed countries in search for work, with the intend to get a better life. Many unskilled labors got job in developed countries after this world war.
But when countries started facing economic crisis many workers started migrating to their home countries. There was land shortage and job shortage at this time. Farmers faced crop failure
Another cause of this migration was civil war that took place in Spain.
Most people migrated to seek religious, political and personal freedom.
This migration was also impacted by global conflicts also.