Thank you very much for your explanation. Now I see.
The underlined part is an adjectival phrase and it's headed by an intensifier:
Ex: How beautiful are the flowers! Cf. How beautiful flowers are!
Ex: What a peaceful city is Hangzhou! Cf. What a peaceful city Hangzhou is!
Ex: How smart you are! Cf. How smart are you! <ambiguity sets in>
How has more than one meaning in that context, so intonation is needed to differentiate the meanings implied by the syntax:
How smart are you? <level of intelligence is questioned>
How smart are you! <level of intelligence is either praised or questioned>
This example isn't headed by an intensifier:
Ex: to help show how intelligent is an animal.
This example is, but it's also ambiguous:
Ex: How intelligent is an animal! Cf. How intelligent an animal is!
The one you're dealing with is housed within a clause; it's an argument of a clause, unlike the examples above which are clauses unto themselves.
Hope that helps.
All the best.
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