How do conditional clauses function in sentences? Give examples.

Conditional clauses, also known as if-clauses, are used to express a condition or a hypothetical situation that must be met for the main clause to occur. These clauses typically begin with the subordinating conjunctions "if," "unless," "provided that," "in case," or "suppose/supposing."

Conditional clauses can be divided into two types: real conditional clauses and unreal conditional clauses.

1. Real Conditional Clauses:
Real conditional clauses express situations that are possible or likely to happen. They consist of two parts: the condition (if-clause) and the result (main clause). The verb tense used in the if-clause determines the verb tense used in the main clause.

Examples:
- If it rains, we will stay at home. (Present simple in the if-clause, future simple in the main clause)
- If I see her, I will tell her the news. (Present simple in the if-clause, future simple in the main clause)
- If you study hard, you will pass the exam. (Present simple in the if-clause, future simple in the main clause)

2. Unreal Conditional Clauses:
Unreal conditional clauses express situations that are hypothetical, contrary to reality, or unlikely to happen. They consist of two parts: the condition (if-clause) and the result (main clause). The verb tense used in the if-clause determines the verb tense used in the main clause, but with a modal auxiliary verb to indicate the unreal or hypothetical nature of the situation.

Examples:
- If I were rich, I would travel the world. (Past simple subjunctive "were" in the if-clause, conditional "would" in the main clause)
- If I had studied harder, I would have passed the exam. (Past perfect in the if-clause, conditional perfect in the main clause)
- If she had known, she would have helped us. (Past perfect in the if-clause, conditional perfect in the main clause)

In summary, conditional clauses function in sentences by expressing a condition or hypothetical situation that determines the outcome in the main clause. They can be real or unreal, depending on the likelihood or reality of the situation being described.