(1) as the theme:
It is difficult to finish the work in ten minutes. It is difficult to finish the work in ten minutes.
Losing confidence means failure. Setbacks mean failure.
When an infinitive phrase is used as the subject, it is often used as the formal subject, and the real subject infinitive is placed after the sentence. For example, the above two sentences can take the following forms:
It is difficult to finish the work in ten minutes. It is difficult to finish the work in ten minutes.
It means the failure of losing confidence. Setbacks mean failure.
Commonly used sentence patterns are:
1, It+be+ noun +to do.
It needs someone. Take some time to do sth.
It is +be+ adjective+for someone to do something. Adjectives such as careless, clever, good, stupid, honest, kind, lazy, good, right, stupid, stupid and wise are often used to express praise or criticism, and the sb before the infinitive can be used as its logical subject.