48. The golden crab of the Gulf of Mexico has not been fished commercially in great numbers, primarily on account of living at great depths-- 2,500 to 3,000 feet down.
(A) on account of living
(B) on account of their living
(C) because it lives
(D) because of living
(E) being they live
OG explanation: As used in choices A, B, and D, the phrases on account of and because of are unidiomatic;because, which appears in C and E, is preferable here since because can introduce a complete subordinate clause explaining the reson why the golden crab has not been fished extensively.....Choice D, like A, fail to provide a noun or pronoun to perform the action of living, but even with its the phrease would e more awkward and less clear than it lives
问题1：why on account of and because of are unidiomatic
问题2：D和A中，living 的主语不可以直接看作主句主语么？谢谢 | 
