求助两道prep题，感激不尽~

zhoujoy

23.    (28303-!-item-!-188;#058&003943)
A product that represents a clear technological advance over competing products can generally command a high price. Because technological advances tend to be quickly surpassed and companies want to make large profits while they still can, many companies charge the maximum possible price for such a product.  But large profits on the new product will give competitors a strong incentive to quickly match the new product's capabilities.  Consequently, the strategy to maximize overall profit from a new product is to charge less than the greatest possible price.
In the argument above, the two portions in boldface play which of the following roles?
(A) The first is a consideration that has been raised to argue that a certain strategy is counterproductive; the second presents that strategy.
(B) The first is a consideration raised to support the strategy that the argument recommends; the second presents that strategy.
(C) The first is a consideration raised to explain the appeal of a certain strategy; the second presents that strategy.
(D) The first is an assumption, rejected by the argument, that has been used to justify a course of action; the second presents that course of action.
(E) The first is a consideration that has been used to justify pursuing a goal that the argument rejects; the second presents a course of action that has been adopted in pursuit of that goal.

？50.    (33327-!-item-!-188;#058&007566)
When people evade income taxes by not declaring taxable income, a vicious cycle results.  Tax evasion forces lawmakers to raise income tax rates, which causes the tax burden on nonevading taxpayers to become heavier.  This, in turn, encourages even more taxpayers to evade income taxes by hiding taxable income.   Assumption
The vicious cycle described above could not result unless which of the following were true?
(A) An increase in tax rates tends to function as an incentive for taxpayers to try to increase their pretax incomes.
(B) Some methods for detecting tax evaders, and thus recovering some tax revenue lost through evasion, bring in more than they cost, but their success rate varies from year to year.
(C) When lawmakers establish income tax rates in order to generate a certain level of revenue, they do not allow adequately for revenue that will be lost through evasion.
(D) No one who routinely hides some taxable income can be induced by a lowering of tax rates to stop hiding such income unless fines for evaders are raised at the same time.
(E) Taxpayers do not differ from each other with respect to the rate of taxation that will cause them to evade taxes.
c去not 后怎么感觉是加强呢？