Apartment buildings can be <strike>built on</strike> several floors high and on every floor several apartments can be constructed. <strike>So</strike> Therefore they are probably <strike>are</strike> capable of allowing more than a hundred families in them. <strike>And</strike> Another way <strike>by which</strike> we can ensure <strike>the</strike> nature <strike>to</strike> remains untouched <strike>is to</strike> by trying to develop each city of a country so that <strike>a</strike> great crowds of people will not be forced to go to <strike>the big </strike>larger cities for <strike>the great </strike>better job opportunities.  <strike>they offer</strike>. This way every city can have a balanced population and authorities will<strike> be able not</strike> not need to touch the countryside.

Tnx in advance for correcting it.

Interesting topic! I would suggest adding a topic sentence at the beginning of the paragraph to help tie the topics together. :)