https://forum.english.best/t/it-is-to-v-ving/50930
有一件事情我始終不明白。
1. To V ...
2. Ving ...
3. It is ... to V ...
4. It is ... Ving ...
台灣的中學英文只教1, 2, 3的用法。
4不但不教，還有老師把它列為錯誤的誘答選項。
https://forum.wordreference.com/threads/it-is-adjective-to-v-or-ving.3897776/
#4 is acceptable.
In fact, the least acceptable is #1. While it is grammatically sound, it
feels awkward and unidiomatic. We generally only use that syntax in formal
and very literary contexts.