Reasons for choosing to study in Australia. Since Australia is a country that uses English as the ["it's" is more natural] official language, it can actually be used in everyday life. [The passive construction in the last clause of this sentence is correctly constructed, but an active construction would be better. Consider instead, "one can actually use English in everyday life". Active voice is better.] There is an efficient public transportation system likely to be convenient to use, and it covers all areas [This is a statement of fact? You know that the public transit system covers all areas? It sounds like a statement of fact.]. There is a diverse culture as it is a country of people of many nationalities, which makes for a country with a beautiful and impressive nature. [<-- Here I'm not sure what you were referring to by "which", but I made a guess.] In addition, Australia is not too far from Thailand, and so it's easier than other countries to travel there, internationally, round trip.

Reasons for choosing to study in Australia. Since Australia is a country that uses English as the official language, it can actually be used in everyday life. There is an efficient public transportation system likely,convenient to use and covering all areas.There is a diverse culture as it is a country behavior by many nationalities. Which is a beautiful and impressive nature.In addition, Australia is not too far from Thailand and more easier than another country to travel international round trip.

Reasons for choosing to study in Australia. Since Australia is a country that uses English as the official language, it can actually be used in everyday life. There is an efficient public transportation system likely to be convenient to use and covering all areas. There is a diverse culture as it is a country of many nationalities, which is beautiful and impressive. In addition, Australia is not too far from Thailand and more easier than another countries to travel on an international round trip.