PREP2-14

YuCongyun

Most household appliances use electricity only when in use.  Many microwave ovens, however, have built-in clocks and so use some electricity even when they are not in use.  The clocks each consume about 45 kilowatt-hours per year.  Therefore, households whose microwave oven has no built-in clock use 45 kilowatt-hours per year less, on average, than do comparable households whose microwave oven is otherwise similar but has a built-in clock.

 

Which of the following is an assumption on which the argument depends?

 

(A) Households that do not have a microwave oven use less energy per year, on average, than do households that have a microwave oven.

(B) Microwave ovens with a built-in clock do not generally cost more to buy than microwave ovens without a built-in clock.

(C) All households that have a microwave oven also have either a gas oven or a conventional electric oven.

(D) Households whose microwave oven does not have a built-in clock are no more likely to have a separate electric clock plugged in than households whose microwave oven has one.

(E) There are more households that have a microwave oven with a built-in clock than there are households that have a microwave oven without a built-in clock.

各位战友，这道题为什么选D？A呢？

YuCongyun

求救!

hansomecd

说你吃一个青菜面5块钱比你吃一个大排面8块钱要便宜。

前提就是你吃青菜面就吃饱了，如果你没吃饱，再加个鸡腿5块钱，就比一个大排面吃饱了还贵。

题目讨论的是 有表的炉子跟没表的炉子，不是讨论有炉子的家庭跟没炉子的家庭。A无关

a2710

诚心请问(D)该如何解释?

gtr

Most household appliances use electricity only when in use.  Many microwave ovens, however, have built-in clocks and so use some electricity even when they are not in use.  The clocks each consume about 45 kilowatt-hours per year.  Therefore, households whose microwave oven has no built-in clock use 45 kilowatt-hours per year less, on average, than do comparable households whose microwave oven is otherwise similar but has a built-in clock.
Which of the following is an assumption on which the argument depends?
(A) Households that do not have a microwave oven use less energy per year, on average, than do households that have a microwave oven.

(B) Microwave ovens with a built-in clock do not generally cost more to buy than microwave ovens without a built-in clock.

(C) All households that have a microwave oven also have either a gas oven or a conventional electric oven.

(D) Households whose microwave oven does not have a built-in clock are no more likely to have a separate electric clock plugged in than households whose microwave oven has one.

(E) There are more households that have a microwave oven with a built-in clock than there are households that have a microwave oven without a built-in clock.
各位战友，这道题为什么选D？A呢？

-- by 会员 YuCongyun (2009/3/28 2:56:00)

让我先把这题目写出来：
事实：有时钟的微波炉，里面的时钟一年要消耗45瓦点
结论：对于一个家庭而言，有时钟的微波炉要比没时钟的微波炉一年多用45瓦电。
问题：这个结论的假设是什么？
A: 没有微波炉的家庭用电比有微波炉的家庭少。
D：如果一个家庭买了一个没有时钟的微波炉，它不会去买一个单独的耗电的时钟。
解题：很明显我们需要D才能让结论成立啊。如果一个家庭买了不带闹钟的微波炉，然后又单独买了一个时钟，最后得不偿失，可能更费电。所以，要省电，关键在于买不带时钟的微波炉的家庭不能去买独立的时钟。
A是一个迷惑但不相干的选项。它对于结论毫无帮助。

a2710

原来如此,感谢gtr伸出援手

frankzheng43

顶楼主！