请教lsat-set6-s2-16,20

sftd

16. The ancient Romans understood the principles of water power very well and in some outlying parts of their empire they made extensive and excellent use of water as an energy sources. This makes it all the more striking that the Romans made do without water power in dominated by large cities.
Which one of the following, if true , contributes most to an explanation of the difference described above in the Romans use of water power?
(A) The ancient Romans were adept at constructing and maintaining aqueducts that could carry quantities of water sufficient to supply large cities over considerable distances
(B) In the areas in which water power was not used water flow in rivers and streams was substantial throughout the year but nevertheless exhibited some seasonal variation
(C) Water power was relatively vulnerable to sabotage but any damage could be quickly and inexpensively repaired
(D) In most areas to which the use of water power was not extended other more traditional sources of energy continued to be used
(E) In heavily populated areas the introduction of water power would have been certain to cause social unrest by depriving large numbers of people of their livelihood

答案为E, 想不通,请高人指点

Policy Adviser: Freedom of speech is not only a basic human right; it is also the only rational policy for this government to adopt. When ideas are openly aired ,good idea flourish, silly proposals are easily recognized as such, and dangerous ideas can be responded to by forcing citizens to disseminate their thoughts in secret.
20. The policy adviser's method of persuasion in recommending a policy of free speech to the following?
(A) a circular justification of the idea of free speech as an idea that flourishes when free speech is allowed
(B) advocating respect for basic rights of citizens for its own sake
(C) a coupling of moral ideals with self-interest
(D) a warning about the difficulty of suppressing the truth
(E) a description of an ideal situation that cannot realistically be achieved.

答案为C, 没看懂.

cranberry

1要找的就是为什么水力不能使用的原因，而ABC都说的是水力的使用是没问题的，D说的是没用水力而用了其他能源，这没解释水力不能使用的原因，只有E

2，我只会用排除法解这道题

brvyw

以下是引用sftd在2003-8-16 16:58:00的发言：

Policy Adviser: Freedom of speech is not only a basic human right; it is also the only rational policy for this government to adopt. When ideas are openly aired ,good idea flourish, silly proposals are easily recognized as such, and dangerous ideas can be responded to by forcing citizens to disseminate their thoughts in secret.
20. The policy adviser's method of persuasion in recommending a policy of free speech to the following?
(A) a circular justification of the idea of free speech as an idea that flourishes when free speech is allowed
(B) advocating respect for basic rights of citizens for its own sake
(C) a coupling of moral ideals with self-interest
(D) a warning about the difficulty of suppressing the truth
(E) a description of an ideal situation that cannot realistically be achieved.

答案为C, 没看懂.

just gives a summary of what he said above; moral ideals refers to human right; its own sake refers to the rest part.