1. Q037
Amy was so happy that she worked overtime last week ____ the car repair bill was $500.
The right choice is ...
, because
, for
; since
; so
The subordinating conjunction because makes sense, but the comma in front of it is wrong. Remember that 99.99% of the time, you will not need a comma with because.
Super choice! The coordinating conjunction for (which means because) does require that comma.
The subordinating conjunction since usually requires no punctuation in this position—but especially not a full stop, which is what the semicolon provides.
So = as a result, which is not logical here.