hafgola wrote:
The Stirling engine is not a photovoltaic system, in which sunlight excites electrons in a semiconductor to generate
electricity; rather a parabolic dish that concentrates solar power, generating heat that is converted to grid-quality electricity.
(A) electricity; rather
(B) electricity, but rather
(C) electricity, but rather that of
(D) electricity, but that of
(E) electricity; it is that of
I have a question on the correct answer
regarding the word BUT, (which is a Coordinating Conjunction (Fanboys word according to Knewton))
I thought that But, And, Yet etc. would connect a Independent clause with a Comma + Coordinating Conjunction
for example. I need to relax, but I have so many things to do.
My question is why is BUT OK in answer B...In B there is no subject or main verb in place after BUT so it can´t be an independent clause ?
I guess the trap is that we see ", but" and expect an independent clause to follow. However, if you take a close look, ", but" does not precede a complete independent clause. In fact, the "," is used as an end to the modifier. Thus, this is a sentence where only one independent clause is separated by a modifying clause, which causes confusing.
The Stirling engine is not a photovoltaic system[highlight], in which sunlight excites electrons in a semiconductor to generate electricity,[/highlight] but rather a parabolic dish that concentrates solar power, generating heat that is converted to grid-quality electricity.
If we get rid of the modifiers:
The Stirling engine is not a photovoltaic system but rather a parabolic dish that concentrates solar power.
Now, we just have one independent clause. This is how we should consider our problem statement.