Here are some important details about subordinating conjunctions:

1. Types of Subordinating Conjunctions:

   • "Because": It indicates the cause or reason for something.
   • "Although" / "Though": It shows a contrast or concession between two ideas.
   • "If": It introduces a conditional clause.
   • "When": It indicates a time relationship or condition.
   • "Since": It expresses a cause or time relationship.
   • "While": It denotes a simultaneous action or condition.
   • "After": It indicates that an action or event occurs following another.
   • "Before": It denotes that an action or event occurs prior to another.
   • "Until": It signifies the continuation of an action or event until a specific time.
   • "For": It introduces a clause indicating the duration of an action or event.

2. Usage:

   • Subordinating conjunctions are used to introduce dependent clauses, which cannot stand alone as complete sentences.
   • They join a dependent clause with an independent clause, and the dependent clause becomes subordinate to the main clause.
   • Example:
     • "He couldn't attend the party because he had to work."
     • "Although it was raining, they decided to go for a walk."
     • "If it rains, we will stay indoors."
     • "I will call you when I arrive at the airport."
     • "Since it was her birthday, we threw a surprise party."
     • "While I was cooking, she set the table."
     • "After she finished her meal, she went for a walk."
     • "Please finish your homework before you play video games."
     • "They will wait at the station until the train arrives."
     • "He stayed up all night for he had an important presentation."

3. Placement:

   • Subordinating conjunctions typically appear at the beginning of the dependent clause.
   • Example:
     • "Because I was tired, I went to bed early."

4. Punctuation:

   • When a dependent clause comes before an independent clause, a comma is generally used to separate them.
   • Example:
     • "After he finished his homework, he played video games."

Subordinating conjunctions play a crucial role in indicating relationships between different parts of a sentence. They help establish the hierarchy of ideas and convey the dependency or subordination of one clause to another. Understanding and using subordinating conjunctions correctly will enable you to construct well-formed and cohesive sentences with complex structures and varied relationships between ideas.