gwd2-27困惑阿~

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Q27:

       先是不知道这个问题提的是什么意思？

       再是不知道为什么选这个？请教阿~~~

    

Rye sown in the fall and plowed into the soil in early
spring leaves a residue that is highly effective at controlling broad-leaved
weeds, but unfortunately for only about 45 days.  No major agricultural crop matures from seed
in as little as 45 days.  Synthetic
herbicides, on the other hand, although not any longer-lasting, can be
reapplied as the crop grows.  Clearly,
therefore, for major agricultural crops, plowing rye into the soil can play no
part in effective weed control.

    

 

    

The argument is most vulnerable to
the objection that it fails to

    

 

    

1. consider that there might be minor,
        quick-growing crops that do mature in 45 days or less
2. identify any alternative method of weed control
        that could be used instead of the method it rejects
3. distinguish among the various kinds of synthetic
        herbicides
4. allow for the possibility of combining the two
        weed-control methods it mentions
5. allow for the possibility that plants other than
        rye, handled the same way, might have the same effect

    

   Answer

gillfiese

Rye sown in the fall and plowed into the soil in early
spring leaves a residue that is highly effective at controlling broad-leaved
weeds, but unfortunately for only about 45 days.  No major agricultural crop matures from seed
in as little as 45 days.  Synthetic
herbicides, on the other hand, although not any longer-lasting, can be
reapplied as the crop grows.  Clearly,
therefore, for major agricultural crops, plowing rye into the soil can play no
part in effective weed control.

题干说Rye(裸麦粒？)会留下residual(残留物)，这种residual可以控制宽叶的weed(杂草),但是45天后失效就不能继续控制了。但是它失效的时候作物还没有成熟呢(杂草就又长出来了)。而合成的herbicides(除草剂)虽然不能持久控制，但却可以不断反复的用来达到持续的控制效果。结论说，Rye对于有效控制weed没有作用。

其实Rye只不过是在作物mature之前就失效了，但是作物mature之前还是很有用的。所以如果和合成herbicides一起用，最开始45天用Rye，后面开始用合成herbicide，势必可以有效的控制weed了。(我觉得Rye好就在于它反正也是要种到地里，它的残留物可以利用来除草，还能用上45天，价值很明显啦，相对的，那45天里面都用合成除草剂不知道要浪费多少钱)

craigchsieh

D是很好没错，那A呢？在A的情况下rye能起作用 effective weed control，不就可以削弱结论了吗？

yi11

(A)的问题在于结论说"for  major agriculture crops"，但是(A)说可能有minor crops如何，和结论无关。

52element

以下是引用yi11在2008-8-6 22:24:00的发言：
(A)的问题在于结论说"for  major agriculture crops"，但是(A)说可能有minor crops如何，和结论无关。

豁然开朗，谢谢。

freedx

顶！我也错在A……