Introductory it as Object
5.3 V it adj whThe verb is followed by it, an adjective group, and a wh-clause.
These verbs are concerned with leaving a situation unclear or doubtful, or making it clear or obvious.
The failure of many republics to take part leaves it unclear whether any laws passed by this new Parliament will be valid throughout the country.
On the very first day, the United Nations made it absolutely clear what he should do.
The passive pattern is it be V-ed adj wh, where it is the Subject of the clause.
It has not been made clear whether the invitation was extended before or after the coup.