1. Yes, it is necessary for everyone to be literate person.
2. I think these two subjects should be together.
3. To practise using new worlds is undoubtedly better.
4. Its not difficult to me to learn them.
5. Because not knowing idioms you can have difficulty in communicating.
6. Because if you are using the uncorrect intonation, people may perceive your words wrong.
7. Well, this is useful if you have not heard the whole phrase to understand that saying a person had in mind.
8. You can daily communicate with foreigners, for example, in Skype.
9. In my opinion, the most difficult - the study of verb forms.
10. In all likelihood, this expression means the language which society communicates at.