答案给的E,看了讨论贴，说原文接近C,我开始选E,现在也觉得C对。从意义上讲，应该是boundary prevent

而E的意思是sound prevent its energy from dissipate。 请大家指教！

Sound can travel through water for enormous distances,

prevented from dissipating its acoustic energy as a result of

boundaries in the ocean created by water layers of different

temperatures and densities.

A.      prevented from dissipating its acoustic energy as a

result of

B.  prevented from having its acoustic energy dissipated by

C.  its acoustic energy prevented from dissipating by

D.  its acoustic energy prevented from being dissipated as

a result of

E   preventing its acoustic energy from dissipating by

answer:

E项是正确的。声波本身的特质就是在水中的衰减非常小，boundaries会令声波衰减，

而不是让声波不衰减，C，D项错在把boundaries当好人了。

preventing作伴随状语，把它调到句首就十分容易理解了。

Preventing its acoustic energy from dissipating by boundaries in the ocean

created by water layers of different temperatures and densities, sound can

travel through water for enormous distances.

逻辑上可以理解为：因为能量不被水减弱，声波可能传千里。