6. Solar energy production has made huge strides in recent years, _______ advances in photovoltaic technologies the underpinnings of solar panels have made it easier and cheaper to harness energy from the sun.
(A) despite
(B) unless
(C) while
(D) as
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統計: A(2), B(4), C(5), D(21), E(0) #3249751
統計: A(2), B(4), C(5), D(21), E(0) #3249751