"Republicans" and "Democrats" should NOT be capitalized."Party's" should be "parties.""Presidential" should NOT be capitalized.There shouldn't be commas around "Republicans and Democrats."
"Presidential" is never capitalized.
And "president" is capitalized only in front of a name as a title, e.g., "President Barack Obama," BUT "Barack Obama, the president."
"Never mind" is always two words.
Nevermind is an album by Nirvana.
Adding commas around "Jackie," i.e., appositive commas, would show that her name is nonessential to the meaning of the sentence because Brian has only one sister and it is therefore unnecessary to say her name. Without the commas, the name specifies which of Brian's sisters is coming to dinner.
GrammarPunctuationSpellingNone of the Above
You need a possessive in "each other's," i.e., "They're so compatible they finish each other's sentences." Neither "each others" nor "each others'" exist.
You "lay" down an object.
In the present tense, "lay" requires a direct object, while "lie" does not. For example, "He lies down," BUT "He lays down the books."