例：剑8T4P2—P95 Q17  Biological control of pests

Q17  By the mid-1960s, cotton farmers in Central America found that pesticides

    A  were wiping out 50% of the pests plaguing the crops.

    B  were destoying 50% of the crops they were meant to protect.

    C  were causing a 50% increase in the number of new pests reported.

    D  were costing 50% of the total amount they spent on their crops.

首先：划定位词，定位题目出处： mid-1960s 和 50%

其次：找出4个备选项的分歧点

     从题目中可看到，4选项都有50%，所以50%所限定的词为各备选项的实质。

     A  50% of the pests (害虫)

     B  50% of the crops（庄稼）

     C  50% of new pests （新害虫）

     D  cost, spent ==$ (钱)  so  50% of $

最后：看原文，找证据支持某选项

    “Bythe mid-1960s(=Q17), the situation took an alarm turn with the outbreak of four more new pests, necessitating pesticide spraying to such an extent that50% of financial outlayon cotton production was acounted for by pesticieds. ”

     解析：虽然我们不认识“outlay”的含义，但是这并不影响我们做题，“financial金融的，财政的”，与“$”有关，所以选D。