Because it is a skill that demonstrates that a clear knowledge of the language spoken. And because he is the skill to convey ideas. Understanding and using language to communicate in everyday life.
Since it is a skill that shows that speak a clear language knowledge. And the verbal skills to convey an understanding and feeling for the language used to communicate on a daily basis.
Because is a skill that shows that the speaker has the language knowledge clearly. And because the skills of speaking a convey the ideas, understanding and feeling in the use of language to communicate in daily life.