situational dialects

One of the important missions of historical linguistics is to reconstruct the protolanguage. Please explain what the protolanguage is and how historical linguists reconstruct it.

The basic form of English negative prefix in- is [in-], as in inaccurate and insecure. In impossible, [n] is changed to match the place of articulation of its following stop [p]. In illiterate, [n] becomes identical to its following [1]. Which phonological rule does this example illustrate? Please define the rule and give one more example.

the critical period for language acquisition

situational dialects

negative transfer

selectional restrictions

clipping

illocutionary act

minimal pair

inflectional affixes