(4 points) Consider a language for simplified email addresses. The address has three parts. The first part is an account name starting with a letter and continuing with any number of letters or digits. The second part is an @ character. The third part is a host with two or more sequences of letters or digits separated by periods; the last sequence must be a top-level domaineither com, org, gov, or net. Define a context-free grammar to model this language.

(4 points) The following grammar defines the scientific notation for non-negative floating point numbers. It is in the E-BNF notation and [, ], (, ), |, {, and } are meta-symbols of E-BNF. Convert this E-BNF grammar to a BNF grammar. -> [E] -> [.] -> [(+|-)] -> {} -> 0 | -> 1 | 2 | ... | 9