¶ … feature of language and why? The most important key feature of any language is grammar. Grammar provides structure and meaning to sounds. Without a grammatical framework, it is unclear if a word is referring to a noun or an adjective; an adverb or a verb. Even a computer language must have a grammatical construction to be read and to be comprehensible. Many words between different languages sound very similar (such as Latin and Portuguese, for example) but without grammatical rules the distinctions in use between those sounds is unclear. Grammar also is part of the social 'situation' of a language. For a language to be effective, it cannot exist in a vacuum. "No commonly-spoken language is fixed. All languages change over time. What we call 'grammar' is simply a reflection of a language at a particular time" (What is grammar, 2014, English Club). Over time certain grammatical rules may become institutionalized and written down while others remain unspoken yet a vital part of communication.

Q2. Do you think animals meet the definition of using language? There are gorillas who have been trained to use sign language. Do they meet the definition of using language?

Animals clearly use sounds and gestures to communicate. Also, those sounds...

However, words are symbolic representations of language. An animal cannot evoke a concept such as danger in the abstract although it can alert people to specific dangers, like the presence of an intruder through barking. But it cannot tell the human about what type of specific threat exists and on what level. A dog might beg for food or a treat it believes is there in the cupboard but for expressing abstract notions such as hunger or a desire for a specific type of treat through words, animal communication is not adequate. There is also no sense of grammatical construction to animal language for the most part. Even when a gorilla uses sign language, it is making use of a human construction, not something innate to its species.
Q3. What are the factors that make an adult more successful in learning a second language? Is it possible that children are not really better at learning a second language but just different in the way they learn?

Learning another, second language as a child or at least having some rudimentary basis in the sounds and vocabulary of the new second language the adult is attempting to acquire can facilitate leaning. Adults may also benefit from…