Do we have to learn english?

if answer is "yes", why?

or

even though the most spoken languages is spanish, arabic, english, turkish, chinese. why do we speak spanish or arabic ..etc instead of english?

The reason why English is so important as a language is because, it is a very descriptive language when used correctly.

 A good example of this is computer jargon.

Another good example of the descriptive (and important) side of English is that many companies around the world use English as their main language when discussing internal matters.

I.E. BMW use English for their upper management level meetings and above because of this.

 I hope this helps

If there is only one language in the world. How have it changed?

in today's globalization, English is more important as well as Chinese. for the job/life ti be better ,we have to study language such english or chinese well according to the location.   i think everybody could study english well ,but the enviroment is so important!

tommytanker, you are not fully correct. we need to learn english , because it is the most used common language between people from different countries. not only english but every language is discriptive and expressive as long as you are familiar with it. according to e my mothertongue is more expressive than english.so is to everybody. I appreciate Colombian Girl for being discerned on this issue.

I think, English grammar is easier to learn than Romance Languages grammar.

of course,we do.we can choose to learn in a fun way.introduce a site (www.popenglish.tv) to mastery english happily.

because, we don't produce technology and don't explore knowledge. Hence, we have to learn english.

we have to because english is an international language and if we can master one more foreign language we will have more opportunities in the future

The United States invaded the whole world, so, we must learn the language to make sure of its  compulsion

even though the most spoken languages is spanish, arabic, english, turkish, chinese. why do we speak spanish or arabic ..etc instead of english?