Difference between as, since, because and so. Conjunctions

Solution
As, since, because and so are all conjunctions that join the subordinate clause with the main clause in a sentence. In simple words, they connect the result with the reason.

The difference between them is as follows:-

When we use because and so we usually focus on the reason. 

For example in 

1. She agreed to come tomorrow because she has an important meeting today. 
2. She spoke quietly so that Rahul would not hear us.

In both sentences, the focus is on the second clause.

When we use as and since we usually focus on the result.

For example in 

​​​​​1. I hope they will come by tomorrow as I can't wait to see them.
2. The apples are very expensive since they are rare here.

In both sentences the focus is on the first clause.

Amongst other differences,

• because is the most commonly used conjunction and is always used in interrogatory sentences. 

For eg it is wrong to say "Are you ill since you stayed up at night?"
The correct sentence would be "Are you ill because you stayed up at night?"

• As and Since clauses are usually used at the beginning of a sentence. while because and so are not used in the beginning formally.

For eg-  As you already know her, I won't give you an introduction.
Since remote work has become a custom in our company, I don't need to buy formal clothes anymore. 

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