When to use “as”, “for”, “since”?

[dawnngcm]

“As”, “for” and “since” all are used to introduce reasons as “because”, “because of” and “due to” do. However, I cannot figure out their grammar operation.

Can anyone help to explain them?


Many thanks!

 

[sarat_106]

“As”, “for” and “since” all are used to introduce reasons as “because”, “because of” and “due to” do. However, I cannot figure out their grammar operation.

Can anyone help to explain them?


Many thanks!

“since ", “as” and "for", are basically prepositions but when used as conjunction, they agree in implying a reason (which may be direct, casual or justified) for an occurrence or action. As or since are normally used at the beginning while ‘for’ is used at the beginning of the clause introducing the reason: as:

As (or since) I was tired, I was sleeping. (casual implying merely circumstance)
I was sleeping, for I was tired. (introduced the reason, proof, or justification)
As you are leaving last, please turn out the lights. (casual)
Please turn out the lights for you are leaving last (reason for action)
I decided to book into a hotel, for it was getting late, (Reason for action)
She remained silent, for her heart was heavy and her spirits low. (Reason)