introductory it

trouble is a friend yeah trouble is a friend - performed by lenka - hihihi . OK, let we learn about "introductory it"

Introductory "It"
When the subjective is an infinitive phrase:
We begin a sentence with it when the real subject is an infinitive phrase.
So instead of saying, ‘To accept your advice is difficult’, we say, ‘It is difficult to accept your advice’.

Structure: It + verb + subject complement + infinitive phrase (real subject)
It is easy to learn English. (To learn English is easy.)
It is easy to find fault with others. (To find fault with others is easy.)
It is difficult to know his motive. (To know his motive is difficult.)
It is difficult to find a good job during these troubled times.
It is dangerous to play with fire.
It could be dangerous to drive so fast.
Note:
That when we wish to emphasize the infinitive phrase, it may be put at the beginning, especially when it is short