While it may seem that this appears to be the case. The word since does not introduce sufficient conditions. What is happening here is that we realize that the premises are presented as conditional statements and then the conclusion follows from these premises.
As a result, we interpret the since to introduce a condition, when in fact it does not actually do so. For the sake of this type of question however, it can work, but in general, think of "since" as a premise indicator. Look for traditional conditional indicator words when trying to identify sufficient and necessary (such as if and then).
I hope this helps. Please let me know if you have any other questions or would like me to elaborate further.
ankita96June 1, 2020
Could you give an example when the word since is not introducing a sufficient condition?
