Grammatically positive and negative clauses

There is an exercise:

Are the following clauses grammatically positive or negative? Give evidence for your answers.

i You're so negative.

Positive: it can be followed be the negative polarity tag aren't you?.

ii I disagree with all of you.

Positive: it can have so-continuation rather then neither (nor)-continuation like, for example, and so my brother.

iii They're always complaining about things of no importance at all.

Positive: it can be followed by the negative polarity tag aren't they?, and the negative element no (determiner) only affects the noun phrase no importance but not the clause.

iv I can do nothing to help you.

Negative: it can't be followed by the negative polarity tag; it has an equivalent in verbal negation: I can't do anything to help you.

v Never before had they offered such good terms.

Negative: it has an equivalent in verbal negation: They haven't ever offered such good terms.

vi That's absolute nonsense, you brainless ninny.

Positive: it can be followed by the negative polarity tag isn't that?.

vii We finished the job in no time.

Positive: it can be followed by the negative polarity tag didn't we?, and the negative element no (determiner) only affects the noun phrase no time, a complement in the prepositional phrase headed by the preposition in.

viii Everybody hates lying, mealy-mouthed, pontificating little weasels like you.

Positive: there isn't a negative element in that clause to mark it as a negative one.

ix We can't just not answer their letter.

Negative: it can be followed the positive polarity tag can we?, and not in the verb phrase not answer is an adverb modifying the head of that phrase.

x There's hardly any chance of them changing their mind.

Negative: it can be followed by the positive polarity tag is there?, but not by the negative one isn't there?.

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Is my analysis correct?