It is said :
Quote:
There is another structure to do this: nominalizing with the particle NO (の) and adding a second particle, NI (に), to show that it's the topic of the sentence.
The example you mentionned doesn't have any relation to this extract.
For a noun :
- Noun + NI + KYOUMI + GA + ARU or
- Noun + NI + KYOUMI + O + MOTSU"
For a verb :
- Verb + KOTO + NI + KYOUMI + GA + ARU or
- Verb + NO + NI + KYOUMI + GA + ARU or
- Verb + KOTO + NI + KYOUMI + O + MOTSU or
- Verb + NO + NI + KYOUMI + GA + ARU
...に興味が深い (means litterally "the interest in ... is deep" ) is correct. But you can also say
...に深い興味がある or ...に深い興味を持つ "to have a deep interest in..."
You conjugate ARU and MOTSU verbs in present,past, negative, negative past tenses.