Grammar
3. To find your way can be a problem.
2. Smoking is bad for you.
1. You are a student. zx xk
4. “How do you do?” is a greeting.
5 .What she said is not yet known.
6. That we shall be late is certain.
7. It is certain that we shall be late.
Subject(主语)
A sentence serving as subject is called Subject Clause.