How does duality appear in the study of languages, where phonetics and semantics represent dual aspects of communication?

NOTE: This is a multi-part question. Once an answer is submitted, you will be unable to return to this part. Identify the productions of the phrase-structure grammar for each of these languages, where S is the starting symbol.   The set of bit strings containing only 1s Multiple Choice A) S → 1   B) S → 1S and S → λ   C) S → 11 and S → 111

10. Please define a CFG for Natural Language to demonstrate that the following sentences would have very similar derivations and therefore can be well-formed: A beautiful girl sings. A green idea dances.

In general, there are two types of grammars for programming languages, regular and context-free, what is the difference, what is the scope (where are they applied), and how can the use of these grammars produce a higher level of program reliability. Does this higher level of reliability encourage complexity?