Register Shift Synonym Selection Formal ColloquialSet 1

1Match the words that all fit the type of language variation.
2The language of the poem at the start of Remains is informal and casual; another word for this is .....
3Stylistic synonyms differ in.
4Fan bobi-2; Fan qismi-1; Qiyinlik darajasi-1; ..... words are the main source of synonymy and polysemy.
5What's the sinonym of "register" ?